Quantum Physics

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New submissions for Fri, 10 May 24

[1]  arXiv:2405.05326 [pdf, other]

Title: Information revival without backflow: non-causal explanations of non-Markovianity

Authors: Francesco Buscemi, Rajeev Gangwar, Kaumudibikash Goswami, Himanshu Badhani, Tanmoy Pandit, Brij Mohan, Siddhartha Das, Manabendra Nath Bera

Comments: 8 Pages, 1 Figure, Comments are welcome!

Subjects: Quantum Physics (quant-ph)

The study of information revivals, witnessing the violation of certain data-processing inequalities, has provided an important paradigm in the study of non-Markovian processes. Although often used interchangeably, we argue here that the notions of ``revivals'' and ``backflows'', i.e., flows of information from the environment back into the system, are distinct: an information revival can occur without any backflow ever taking place. In this paper, we examine in detail the phenomenon of non-causal revivals and relate them to the theory of short Markov chains and squashed non-Markovianity. As a byproduct, we demonstrate that focusing on processes with actual backflows, while excluding those with only non-causal revivals, resolves the issue of non-convexity of Markovianity, thus enabling the construction of a convex resource theory of genuine non-Markovianity.

[2]  arXiv:2405.05332 [pdf, other]

Title: Barren plateaus are swamped with traps

Authors: Nikita A. Nemkov, Evgeniy O. Kiktenko, Aleksey K. Fedorov

Comments: 9+5 pages

Subjects: Quantum Physics (quant-ph)

Two main challenges preventing efficient training of variational quantum algorithms and quantum machine learning models are local minima and barren plateaus. Typically, barren plateaus are associated with deep circuits, while shallow circuits have been shown to suffer from suboptimal local minima. We point out a simple mechanism that creates exponentially many poor local minima specifically in the barren plateau regime. These local minima are trivial solutions, optimizing only a few terms in the loss function, leaving the rest on their barren plateaus. More precisely, we show the existence of approximate local minima, optimizing a single loss term, and conjecture the existence of exact local minima, optimizing only a logarithmic fraction of all loss function terms. One implication of our findings is that simply yielding large gradients is not sufficient to render an initialization strategy a meaningful solution to the barren plateau problem.

[3]  arXiv:2405.05335 [pdf, ps, other]

Title: Wave Function Collapse, Lorentz Invariance, and the Third Postulate of Relativity

Authors: Edward J. Gillis

Comments: 10 pages

Subjects: Quantum Physics (quant-ph)

The changes that quantum states undergo during measurement are both probabilistic and nonlocal. These two characteristics complement one another to insure compatibility with relativity and maintain conservation laws. Nonlocal entanglement relations provide a means to enforce conservation laws in a probabilistic theory, while the probabilistic nature of nonlocal effects prevents the superluminal transmission of information. In order to explain these measurement-induced changes in terms of fundamental physical processes it is necessary to take these two key characteristics into account. One way to do this is to modify the Schroedinger equation by adding stochastic, nonlinear terms. A number of such proposals have been made over the past few decades. A recently proposed equation based on the assumption that wave function collapse is induced by a sequence of correlating interactions of the kind that constitute measurements has been shown to maintain strict adherence to conservation laws in individual instances, and has also eliminated the need to introduce any new, ad hoc physical constants. In this work it is shown that this modified Schroedinger equation is naturally Lorentz invariant. It is further argued that the additional spacetime structures that it requires provide a way to implement the assumption that spacelike-separated operators (and measurements) commute, and that this assumption of local commutativity should be regarded as a third postulate of relativity.

[4]  arXiv:2405.05337 [pdf, other]

Title: Characterization of errors in a CNOT between surface code patches

Authors: Bálint Domokos, Áron Márton, János K. Asbóth

Subjects: Quantum Physics (quant-ph)

As current experiments already realize small quantum circuits on error corrected qubits, it is important to fully understand the effect of physical errors on the logical error channels of these fault-tolerant circuits. Here, we investigate a lattice-surgery-based CNOT operation between two surface code patches under phenomenological error models. (i) For two-qubit logical Pauli measurements -- the elementary building block of the CNOT -- we optimize the number of stabilizer measurement rounds, usually taken equal to $d$, the size (code distance) of each patch. We find that the optimal number can be greater or smaller than $d$, depending on the rate of physical and readout errors, and the separation between the code patches. (ii) We fully characterize the two-qubit logical error channel of the lattice-surgery-based CNOT. We find a symmetry of the CNOT protocol, that results in a symmetry of the logical error channel. We also find that correlations between X and Z errors on the logical level are suppressed under minimum weight decoding.

[5]  arXiv:2405.05351 [pdf, other]

Title: Optical single-shot readout of spin qubits in silicon

Authors: Andreas Gritsch, Alexander Ulanowski, Jakob Pforr, Andreas Reiserer

Subjects: Quantum Physics (quant-ph)

The digital revolution was enabled by nanostructured devices made from silicon. A similar prominence of this material is anticipated in the upcoming quantum era as the unrivalled maturity of silicon nanofabrication offers unique advantages for integration and up-scaling, while its favorable material properties facilitate quantum memories with hour-long coherence. While small spin-qubit registers have exceeded error-correction thresholds, their connection to large quantum computers is an outstanding challenge. To this end, spin qubits with optical interfaces offer key advantages: they can minimize the heat load and give access to modular quantum computing architectures that eliminate cross-talk and offer a large connectivity via room-temperature photon routing. Here, we implement such an efficient spin-photon interface based on erbium dopants in a nanophotonic resonator. We thus demonstrate optical single-shot readout of a spin in silicon whose coherence exceeds the Purcell-enhanced optical lifetime, paving the way for entangling remote spins via photon interference. As erbium dopants can emit coherent photons in the minimal-loss band of optical fibers, and tens of such qubits can be spectrally multiplexed in each resonator, the demonstrated hardware platform offers unique promise for distributed quantum information processing and the implementation of a quantum internet based on integrated silicon devices.

[6]  arXiv:2405.05416 [pdf, other]

Title: Many-time physics in practice: characterising and controlling non-Markovian quantum stochastic processes

Authors: Gregory A. L. White

Comments: PhD thesis. 279 pages main text, 353 pages total

Subjects: Quantum Physics (quant-ph)

Every year, substantial theoretical and experimental progress is made towards the realisation of a genuinely new computational paradigm in the construction of a quantum computer. But progress is fractal; to make headway is to unearth the next set of obstacles. Decades of work has so far overcome physical, mathematical, engineering, and information theoretic obstacles to produce the remarkable high-fidelity devices we see today. But these devices must be near perfect to be useful. Indeed, advancements so far have precipitated sensitivity to a host of complex dynamical and control-based effects. Chief among these today are non-Markovian memory effects, where interactions between a quantum system and its surrounding environment can give rise to multi-time correlations. In this thesis, we address this issue and formally present a generalisation of quantum process tomography, called process tensor tomography (PTT). This establishes the ability to rigorously and systematically characterise non-Markovian open quantum systems, resolving many long-standing issues in the field. In the first part of this work, we present an original review of the literature and motivate the problem at hand. In the second, we develop the framework of PTT, including experiment design, post-processing algorithms, and both simulated and near-term device demonstrations. In particular, we demonstrate this as a tool for obtaining in-depth diagnostics about the nature and origin of temporal quantum correlations. Lastly, we dedicate our efforts to efficiency and self-consistency. To this effect, we explore theoretically processes with sparse memory structures. We then leverage this to develop various efficient estimation techniques tailored for different settings. The result is a robust and lightweight framework capable of both reconstructing and optimally controlling any non-Markovian open quantum dynamics.

[7]  arXiv:2405.05470 [pdf, other]

Title: Deep thermalization in continuous-variable quantum systems

Authors: Chang Liu, Qi Camm Huang, Wen Wei Ho

Comments: 6+24 pages

Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech)

We uncover emergent universality arising in the equilibration dynamics of multimode continuous-variable systems. Specifically, we study the ensemble of pure states supported on a small subsystem of a few modes, generated by Gaussian measurements on the remaining modes of a globally pure bosonic Gaussian state. We find that beginning from sufficiently complex global states, such as random Gaussian states and product squeezed states coupled via a deep array of linear optical elements, the induced ensemble attains a universal form, independent of the choice of measurement basis: it is composed of unsqueezed coherent states whose displacements are distributed normally and isotropically, with variance depending on only the particle-number density of the system. We further show that the emergence of such a universal form is consistent with a generalized maximum entropy principle, which endows the limiting ensemble, which we call the "Gaussian Scrooge distribution", with a special quantum information-theoretic property of having minimal accessible information. Our results represent a conceptual generalization of the recently introduced notion of "deep thermalization" in discrete-variable quantum many-body systems -- a novel form of equilibration going beyond thermalization of local observables -- to the realm of continuous-variable quantum systems. Moreover, it demonstrates how quantum information-theoretic perspectives can unveil new physical phenomena and principles in quantum dynamics and statistical mechanics.

[8]  arXiv:2405.05481 [pdf, other]

Title: Achieving millisecond coherence fluxonium through overlap Josephson junctions

Authors: Fei Wang, Kannan Lu, Huijuan Zhan, Lu Ma, Feng Wu, Hantao Sun, Hao Deng, Yang Bai, Feng Bao, Xu Chang, Ran Gao, Xun Gao, Guicheng Gong, Lijuan Hu, Ruizi Hu, Honghong Ji, Xizheng Ma, Liyong Mao, Zhijun Song, Chengchun Tang, Hongcheng Wang, Tenghui Wang, Ziang Wang, Tian Xia, Hongxin Xu, Ze Zhan, Gengyan Zhang, Tao Zhou, Mengyu Zhu, Qingbin Zhu, Shasha Zhu, Xing Zhu, Yaoyun Shi, Hui-Hai Zhao, Chunqing Deng

Subjects: Quantum Physics (quant-ph)

Fluxonium qubits are recognized for their high coherence times and high operation fidelities, attributed to their unique design incorporating over 100 Josephson junctions per superconducting loop. However, this complexity poses significant fabrication challenges, particularly in achieving high yield and junction uniformity with traditional methods. Here, we introduce an overlap process for Josephson junction fabrication that achieves nearly 100% yield and maintains uniformity across a 2-inch wafer with less than 5% variation for the phase slip junction and less than 2% for the junction array. Our compact junction array design facilitates fluxonium qubits with energy relaxation times exceeding 1 millisecond at the flux frustration point, demonstrating consistency with state-of-the-art dielectric loss tangents and flux noise across multiple devices. This work suggests the scalability of high coherence fluxonium processors using CMOS-compatible processes, marking a significant step towards practical quantum computing.

[9]  arXiv:2405.05511 [pdf, other]

Title: Investigating impact of bit-flip errors in control electronics on quantum computation

Authors: Subrata Das, Avimita Chatterjee, Swaroop Ghosh

Comments: 9 pages, 9 figures, conference

Subjects: Quantum Physics (quant-ph); Emerging Technologies (cs.ET)

In this paper, we investigate the impact of bit flip errors in FPGA memories in control electronics on quantum computing systems. FPGA memories are integral in storing the amplitude and phase information pulse envelopes, which are essential for generating quantum gate pulses. However, these memories can incur faults due to physical and environmental stressors such as electromagnetic interference, power fluctuations, and temperature variations and adversarial fault injections, potentially leading to errors in quantum gate operations. To understand how these faults affect quantum computations, we conducted a series of experiments to introduce bit flips into the amplitude (both real and imaginary components) and phase values of quantum pulses using IBM's simulated quantum environments, FakeValencia, FakeManila, and FakeLima. Our findings reveal that bit flips in the exponent and initial mantissa bits of the real amplitude cause substantial deviations in quantum gate operations, with TVD increases as high as ~200%. Interestingly, the remaining bits exhibited natural tolerance to errors. We proposed a 3-bit repetition error correction code, which effectively reduced the TVD increases to below 40% without incurring any memory overhead. Due to reuse of less significant bits for error correction, the proposed approach introduces maximum of 5-7% extra TVD in nominal cases. However, this can be avoided by sacrificing memory area for implementing the repetition code.

[10]  arXiv:2405.05560 [pdf, ps, other]

Title: Sudden change of interferometric power for X shape states

Authors: D. Zhu, F. L. Zhang, J. L. Chen

Comments: 11 pages, 8 figures. Comments welcome!

Subjects: Quantum Physics (quant-ph)

Quantum interferometric power (IP) is a discordlike measure. We study the dynamics of IP for two-qubit X shape states under different noisy environments. Our study shows that IP exhibits sudden change, and one side quantum channel is enough for the occurrence of a sudden change of IP. In particular, we show that the initial state having no sudden change of quantum discord exhibits a sudden change of IP under the dynamics of amplitude noise, but the converse is not true. Besides, we also investigate the dynamics of IP under two different kinds of composite noises. Our results also confirm that sudden change of IP occurs under such composite noises.

[11]  arXiv:2405.05624 [pdf, ps, other]

Title: Onset of Quantum Thermalization in Jahn-Teller model

Authors: Yoana R. Chorbadzhiyska, Peter A. Ivanov

Comments: 8 pages, 5 figures

Subjects: Quantum Physics (quant-ph)

We investigate the onset of quantum thermalization in a system governed by the Jahn-Teller Hamiltonian which describes the interaction between a single spin and two bosonic modes. We find that the Jahn-Teller model exhibits a finite-size quantum phase transition between the normal phase and two types of super-radiant phase when the ratios of spin-level splitting to each of the two bosonic frequencies grow to infinity. We test the prediction of the Eigenstate Thermalization Hypothesis in the Jahn-Teller model. We show that the expectation value of the spin observable quickly approaches its long-time average value. We find that the distance between the diagonal ensemble average and the microcanonical ensemble average of the spin observable decreases with the effective thermodynamic parameter. Furthermore, we show that the mean-time fluctuations of the spin observable are small and are inversely proportional to the effective system dimension.

[12]  arXiv:2405.05696 [pdf, other]

Title: Investigating entropic dynamics of complicated cavity QED system

Authors: Hui-hui Miao

Comments: 10 pages, 9 figures

Subjects: Quantum Physics (quant-ph)

Various aspects of entropy of a complicated cavity QED system are explored. Atoms are held in optical cavities through optical tweezers and can jump between different cavities through the tunneling effect. The interaction of atom with the cavity results in electronic transitions and the creation and annihilation of photon. Covalent bond and phonon are introduced into the model. The effect of all kinds of interactions on entropy is studied. At the same time, the von Neumann entropy of different subsystems is compared. The results show that by selectively choosing system parameters, the entropic dynamics can be controlled.

[13]  arXiv:2405.05710 [pdf, ps, other]

Title: On the applicability of Kolmogorov's theory of probability to the description of quantum phenomena. Part I

Authors: Maik Reddiger

Comments: 14 pages, no figures; Keywords: geometric quantum theory, foundations of probability theory, quantum potential, double slit experiment, uncertainty principle

Subjects: Quantum Physics (quant-ph); Mathematical Physics (math-ph)

It is a common view that von Neumann laid the foundations of a "non-commutative probability theory" with his axiomatization of quantum mechanics (QM). As such, it is regarded a generalization of the "classical probability theory" due to Kolmogorov. Outside of quantum physics, however, Kolmogorov's axioms enjoy universal applicability. This raises the question of whether quantum physics indeed requires such a generalization of our conception of probability or if von Neumann's axiomatization of QM was contingent on the absence of a general theory of probability in the 1920s.
In this work I argue in favor of the latter position. In particular, I show that for non-relativistic $N$-body quantum systems subject to a time-independent scalar potential, it is possible to construct a mathematically rigorous theory based on Kolmogorov's axioms and physically natural random variables, which reproduces central predictions of QM. The respective theories are distinct, so that an empirical comparison may be possible. Moreover, the approach can in principle be adapted to other classes of quantum-mechanical models.
Part II of this series will address the projection postulate and the question of measurement in this approach.

[14]  arXiv:2405.05753 [pdf, other]

Title: Manipulating Topological Polaritons in Optomechanical Ladders

Authors: Jia-Kang Wu, Xun-Wei Xu, Hui Jing, Le-Man Kuang, Franco Nori, Jie-Qiao Liao

Comments: 8+15 pages, 3+7 figures

Subjects: Quantum Physics (quant-ph)

We propose to manipulate topological polaritons in optomechanical ladders consisting of an optical Su-Schrieffer-Heeger (SSH) chain and a mechanical SSH chain connected through optomechanical (interchain) interactions. We show that the topological phase diagrams are divided into six areas by four boundaries and that there are four topological phases characterized by the Berry phases. We find that a topologically nontrivial phase of the polaritons is generated by the optomechanical interaction between the optical and mechanical SSH chains even though they are both in the topologically trivial phases. Counter-intuitively, six edge states appear in one of the topological phases with only two topological nontrivial bands, and some edge states are localized near but not at the boundaries of an open-boundary ladder. Moreover, a two-dimensional Chern insulator with higher Chern numbers is simulated by introducing proper periodical adiabatic modulations of the driving amplitude and frequency. Our work not only opens a route towards topological polaritons manipulation by optomachanical interactions, but also will exert a far-reaching influence on designing topologically protected polaritonic devices.

[15]  arXiv:2405.05756 [pdf, other]

Title: Everything is Entangled in Quantum Mechanics: Are the Orthodox Measures Physically Meaningful?

Authors: Christian de Ronde, Raimundo Fernandez Moujan, Cesar Massri

Comments: arXiv admin note: text overlap with arXiv:2404.14891

Subjects: Quantum Physics (quant-ph); History and Philosophy of Physics (physics.hist-ph)

Even though quantum entanglement is today's most essential concept within the new technological era of quantum information processing, we do not only lack a consistent definition of this kernel notion, we are also far from understanding its physical meaning [35]. These failures have lead to many problems when attempting to provide a consistent measure or quantification of entanglement. In fact, the two main lines of contemporary research within the orthodox literature have created mazes where inconsistencies and problems are found everywhere. While the operational-instrumentalist approach has failed to explain how inequalities are able to distinguish the classical from the quantum, the geometrical approach has failed to provide a consistent meaningful account of their entropic measure. Taking distance from orthodoxy, in this work we address the quantification and measure of quantum entanglement by considering a recently presented objective-invariant definition in terms of the coding of intensive relations [21] which allows to escape the widespread relativist account of bases and factorizations [24, 25]. Going beyond the orthodox dualistic reference to "quantum particles" and "clicks" in detectors, we will argue that this new line of research is capable not only to evade the many open problems which appear within the mainstream literature, but is also able to present a consistent and coherent physical understanding of entanglement. The main conclusion of this work is that in quantum mechanics -- contrary to what is generally presupposed -- all operational expressions found within the laboratory are intrinsically entangled.

[16]  arXiv:2405.05785 [pdf, other]

Title: Quantum Resource Theories beyond Convexity

Authors: Roberto Salazar, Jakub Czartowski, Ricard Ravell Rodríguez, Grzegorz Rajchel-Mieldzioć, Paweł Horodecki, Karol Życzkowski

Comments: 40 pages, 18 figures

Subjects: Quantum Physics (quant-ph)

A class of quantum resource theories, based on non-convex star-shape sets, presented in this work captures the key quantum properties that cannot be studied by standard convex theories. We provide operational interpretations for a resource of this class and demonstrate its advantage to improve performance of correlated quantum discrimination tasks and testing of quantum combs. Proposed techniques provide useful tools to describe quantum discord, total correlations in composite quantum systems and to estimate the degree of non-Markovianity of an analyzed quantum dynamics. Other applications include the problem of unistochasticity of a given bistochastic matrix, with relevance for quantization of classical dynamics and studies of violation of CP-symmetry in high energy physics. In all these cases, the non-linear witnesses introduced here outperform the standard linear witnesses. Importance of our findings for quantum information theory is also emphasized.

[17]  arXiv:2405.05794 [pdf, other]

Title: Quantum vs. classical $P$-divisibility

Authors: Fabio Benatti, Giovanni Nichele, Dariusz Chruściński

Subjects: Quantum Physics (quant-ph); Mathematical Physics (math-ph)

$P$-divisibility is a central concept in both classical and quantum non-Markovian processes; in particular, it is strictly related to the notion of information backflow. When restricted to a fixed commutative algebra generated by a complete set of orthogonal projections, any quantum dynamics naturally provides a classical stochastic process. It is indeed well known that a quantum generator gives rise to a $P$-divisible quantum dynamics if and only if all its possible classical reductions give rise to divisible classical stochastic processes. Yet, this property does not hold if one classically reduces the quantum dynamical maps instead of their generators: for a unitary dynamics, as an example, $P$-divisibility of its classical reduction is inevitably lost, which is thus, non-Markovian and exhibits information backflow. Instead, for some important classes of purely dissipative evolutions, quantum $P$-divisibility always implies classical $P$-divisibility and thus lack of information backflow both in the quantum and classical scenarios. On the contrary, for a wide class of orthogonally covariant qubit dynamics, we show that loss of classical $P$-divisibility can originate from the classical reduction of a purely dissipative $P$-divisible quantum dynamics as in the unitary case. Moreover, such an effect can be interpreted in terms of information backflow, the information coming in being stored in the coherences of the time-evolving quantum state.

[18]  arXiv:2405.05796 [pdf, other]

Title: Quantum sensing of time dependent electromagnetic fields with single electron excitations

Authors: H. Souquet-Basiège, B. Roussel, G. Rebora, G. Ménard, I. Safi, G. Fève, P. Degiovanni

Comments: 31 pages, 15 figures

Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

In this study, we investigate the potential of electronic interferometers for probing the quantum state of electromagnetic radiation on a chip at sub-nanosecond time scales. We propose to use single electron excitations propagating within an electronic Mach-Zehnder interferometer in the Aharonov-Bohm dominated regime. We discuss how information about the quantum state of the electromagnetic radiation is encoded into the interference contribution to the average outgoing electrical current. By investigating squeezed radiation and single edge magnetoplasmons probed by Leviton pulses in a realistic setup, we show that single electron interferometers have the potential to probe quantum radiation in the time domain with sub-nanosecond to pico-second time resolution. Our research could have significant implications for probing the fundamental properties of light in the microwave to tera-Hertz domains at extremely short time scales.

[19]  arXiv:2405.05825 [pdf, other]

Title: Measurement-based Verification of Quantum Markov Chains

Authors: Ji Guan, Yuan Feng, Andrea Turrini, Mingsheng Ying

Subjects: Quantum Physics (quant-ph)

Model-checking techniques have been extended to analyze quantum programs and communication protocols represented as quantum Markov chains, an extension of classical Markov chains. To specify qualitative temporal properties, a subspace-based quantum temporal logic is used, which is built on Birkhoff-von Neumann atomic propositions. These propositions determine whether a quantum state is within a subspace of the entire state space. In this paper, we propose the measurement-based linear-time temporal logic MLTL to check quantitative properties. MLTL builds upon classical linear-time temporal logic (LTL) but introduces quantum atomic propositions that reason about the probability distribution after measuring a quantum state. To facilitate verification, we extend the symbolic dynamics-based techniques for stochastic matrices described by Agrawal et al. (JACM 2015) to handle more general quantum linear operators (super-operators) through eigenvalue analysis. This extension enables the development of an efficient algorithm for approximately model checking a quantum Markov chain against an MLTL formula. To demonstrate the utility of our model-checking algorithm, we use it to simultaneously verify linear-time properties of both quantum and classical random walks. Through this verification, we confirm the previously established advantages discovered by Ambainis et al. (STOC 2001) of quantum walks over classical random walks and discover new phenomena unique to quantum walks.

[20]  arXiv:2405.05869 [pdf, ps, other]

Title: Comment on: Testing the speed of the spooky action at a distance in a tabletop experiment. [Sci Rep 13, 8201 (2023)]

Authors: Bruno Cocciaro, Sandro Faetti, Leone Fronzoni

Comments: 3 pages, 1 figure

Subjects: Quantum Physics (quant-ph)

In 1989, Eberhard proposed a v-causal model where quantum correlations between entangled particles are established by communications moving at a superluminal speed v_t > c in a preferred frame. In successive years, several experiments established lower bounds for the possible tachyons velocities. In a recent paper, Luigi Santamaria Amato et al. performed an interesting east-west aligned tabletop experiment under the assumption that the preferred frame is the Cosmic Microwave Background (CMB). In that paper, they criticize long-distance experiments but here we show that most of their criticisms are not applicable to long-distance tunnel experiments where the highest lower bound was obtained.

[21]  arXiv:2405.05875 [pdf, other]

Title: A Genetic Approach to Minimising Gate and Qubit Teleportations for Multi-Processor Quantum Circuit Distribution

Authors: Oliver Crampton, Panagiotis Promponas, Richard Chen, Paul Polakos, Leandros Tassiulas, Louis Samuel

Comments: 9 pages, 9 figures

Subjects: Quantum Physics (quant-ph)

Distributed Quantum Computing (DQC) provides a means for scaling available quantum computation by interconnecting multiple quantum processor units (QPUs). A key challenge in this domain is efficiently allocating logical qubits from quantum circuits to the physical qubits within QPUs, a task known to be NP-hard. Traditional approaches, primarily focused on graph partitioning strategies, have sought to reduce the number of required Bell pairs for executing non-local CNOT operations, a form of gate teleportation. However, these methods have limitations in terms of efficiency and scalability. Addressing this, our work jointly considers gate and qubit teleportations introducing a novel meta-heuristic algorithm to minimise the network cost of executing a quantum circuit. By allowing dynamic reallocation of qubits along with gate teleportations during circuit execution, our method significantly enhances the overall efficacy and potential scalability of DQC frameworks. In our numerical analysis, we demonstrate that integrating qubit teleportations into our genetic algorithm for optimising circuit blocking reduces the required resources, specifically the number of EPR pairs, compared to traditional graph partitioning methods. Our results, derived from both benchmark and randomly generated circuits, show that as circuit complexity increases - demanding more qubit teleportations - our approach effectively optimises these teleportations throughout the execution, thereby enhancing performance through strategic circuit partitioning. This is a step forward in the pursuit of a global quantum compiler which will ultimately enable the efficient use of a 'quantum data center' in the future.

[22]  arXiv:2405.05888 [pdf, other]

Title: Quantum entanglement enables single-shot trajectory sensing for weakly interacting particles

Authors: Zachary E. Chin, David R. Leibrandt, Isaac L. Chuang

Comments: 6 pages (2 figures) + 1 page Supplemental Material

Subjects: Quantum Physics (quant-ph)

Sensors for mapping the trajectory of an incoming particle find important utility in experimental high energy physics and searches for dark matter. For a quantum sensing protocol that uses projective measurements on a multi-qubit sensor array to infer the trajectory of an incident particle, we show that entanglement can dramatically reduce the particle-sensor interaction strength $\theta$ required for perfect trajectory discrimination. Within an interval of $\theta$ above this reduced threshold, any unentangled sensor requires $\Theta(\log(1/\epsilon))$ repetitions of the protocol to estimate the particle trajectory with $\epsilon$ error probability, whereas an entangled sensor can succeed with zero error in a single shot.

[23]  arXiv:2405.05892 [pdf, other]

Title: An RNN-policy gradient approach for quantum architecture search

Authors: Gang Wang, Bang-Hai Wang, Shao-Ming Fei

Comments: Comments are welcome

Subjects: Quantum Physics (quant-ph)

Variational quantum circuits are one of the promising ways to exploit the advantages of quantum computing in the noisy intermediate-scale quantum technology era. The design of the quantum circuit architecture might greatly affect the performance capability of the quantum algorithms. The quantum architecture search is the process of automatically designing quantum circuit architecture, aiming at finding the optimal quantum circuit composition architecture by the algorithm for a given task, so that the algorithm can learn to design the circuit architecture. Compared to manual design, quantum architecture search algorithms are more effective in finding quantum circuits with better performance capabilities. In this paper, based on the deep reinforcement learning, we propose an approach for quantum circuit architecture search. The sampling of the circuit architecture is learnt through reinforcement learning based controller. Layer-based search is also used to accelerate the computational efficiency of the search algorithm. Applying to data classification tasks we show that the method can search for quantum circuit architectures with better accuracies. Moreover, the circuit has a smaller number of quantum gates and parameters.

[24]  arXiv:2405.05912 [pdf, other]

Title: Generalized Rényi entropy accumulation theorem and generalized quantum probability estimation

Authors: Amir Arqand, Thomas A. Hahn, Ernest Y.-Z. Tan

Subjects: Quantum Physics (quant-ph)

The entropy accumulation theorem, and its subsequent generalized version, is a powerful tool in the security analysis of many device-dependent and device-independent cryptography protocols. However, it has the drawback that the finite-size bounds it yields are not necessarily optimal, and furthermore it relies on the construction of an affine min-tradeoff function, which can often be challenging to construct optimally in practice. In this work, we address both of these challenges simultaneously by deriving a new entropy accumulation bound. Our bound yields significantly better finite-size performance, and can be computed as an intuitively interpretable convex optimization, without any specification of affine min-tradeoff functions. Furthermore, it can be applied directly at the level of R\'enyi entropies if desired, yielding fully-R\'enyi security proofs. Our proof techniques are based on elaborating on a connection between entropy accumulation and the frameworks of quantum probability estimation or $f$-weighted R\'enyi entropies, and in the process we obtain some new results with respect to those frameworks as well.

[25]  arXiv:2405.05946 [pdf, other]

Title: Motion from Measurement: The Role of Symmetry of Quantum Measurements

Authors: Luka Antonic, Yariv Kafri, Daniel Podolsky, Ari M. Turner

Comments: 20 pages, 11 figures

Subjects: Quantum Physics (quant-ph); Other Condensed Matter (cond-mat.other); Statistical Mechanics (cond-mat.stat-mech)

In quantum mechanics, measurements are dynamical processes and thus they should be capable of inducing currents. The symmetries of the Hamiltonian and measurement operator provide an organizing principle for understanding the conditions for such currents to emerge. The central role is played by the inversion and time-reversal symmetries. We classify the distinct behaviors that emerge from single and repeated measurements, with and without coupling to a dissipative bath. While the breaking of inversion symmetry alone is sufficient to generate currents through measurements, the breaking of time-reversal symmetry by the measurement operator leads to a dramatic increase in the magnitude of the currents. We consider the dependence on the measurement rate and find that the current is non-monotonic. Furthermore, nondegenerate measurements can lead to current loops within the steady state even in the Zeno limit.

[26]  arXiv:2405.05958 [pdf, ps, other]

Title: Stability of slow Hamiltonian dynamics from Lieb-Robinson bounds

Authors: Daniele Toniolo, Sougato Bose

Comments: 10 pages plus references, 1 theorem, 3 figures

Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Strongly Correlated Electrons (cond-mat.str-el); Mathematical Physics (math-ph)

We rigorously show that a local spin system giving rise to a slow Hamiltonian dynamics is stable against generic, even time-dependent, local perturbations. The sum of these perturbations can cover a significant amount of the system's size. The stability of the slow dynamics follows from proving that the Lieb-Robinson bound for the dynamics of the total Hamiltonian is the sum of two contributions: the Lieb-Robinson bound of the unperturbed dynamics and an additional term coming from the Lieb-Robinson bound of the perturbations with respect to the unperturbed Hamiltonian. Our results are particularly relevant in the context of the study of the stability of Many-Body-Localized systems, implying that if a so called ergodic region is present in the system, to spread across a certain distance it takes a time proportional to the exponential of such distance. The non-perturbative nature of our result allows us to develop a dual description of the dynamics of a system. As a consequence we are able to prove that the presence of a region of disorder in a ergodic system implies the slowing down of the dynamics in the vicinity of that region.

[27]  arXiv:2405.05965 [pdf, other]

Title: Quantum Communication and Mixed-State Order in Decohered Symmetry-Protected Topological States

Authors: Zhehao Zhang, Utkarsh Agrawal, Sagar Vijay

Comments: 27 pages, 8 figures

Subjects: Quantum Physics (quant-ph); Strongly Correlated Electrons (cond-mat.str-el)

Certain pure-state symmetry-protected topological orders (SPT) can be used as a resource for transmitting quantum information. Here, we investigate the ability to transmit quantum information using decohered SPT states, and relate this property to the "strange correlation functions" which diagnose quantum many-body orders in these mixed-states. This perspective leads to the identification of a class of quantum channels -- termed symmetry-decoupling channels -- which do not necessarily preserve any weak or strong symmetries of the SPT state, but nevertheless protect quantum many-body order in the decohered mixed-state. We quantify the ability to transmit quantum information in decohered SPT states through the coherent quantum information, whose behavior is generally related to a decoding problem, whereby local measurements in the system are used to attempt to "learn" the symmetry charge of the SPT state before decoherence.

Cross-lists for Fri, 10 May 24

[28]  arXiv:2405.05316 (cross-list from cond-mat.str-el) [pdf, other]

Title: Higher Berry Curvature from the Wave Function I: Schmidt Decomposition and Matrix Product States

Authors: Ophelia Evelyn Sommer, Xueda Wen, Ashvin Vishwanath

Comments: 9 pages, 2 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)

Higher Berry curvature (HBC) is the proposed generalization of Berry curvature to infinitely extended systems. Heuristically HBC captures the flow of local Berry curvature in a system. Here we provide a simple formula for computing the HBC for extended $d = 1$ systems at the level of wave functions using the Schmidt decomposition. We also find a corresponding formula for matrix product states (MPS), and show that for translationally invariant MPS this gives rise to a quantized invariant. We demonstrate our approach with an exactly solvable model and numerical calculations for generic models using iDMRG

[29]  arXiv:2405.05322 (cross-list from cond-mat.mes-hall) [pdf, other]

Title: Nodal Spectral Functions Stabilized by Non-Hermitian Topology of Quasiparticles

Authors: Carl Lehmann, Tommaso Micallo, Jan Carl Budich

Comments: 12 pages, 9 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Strongly Correlated Electrons (cond-mat.str-el); Quantum Physics (quant-ph)

In quantum materials, basic observables such as spectral functions and susceptibilities are determined by Green's functions and their complex quasiparticle spectrum rather than by bare electrons. Even in closed many-body systems, this makes a description in terms of effective non-Hermitian (NH) Bloch Hamiltonians natural and intuitive. Here, we discuss how the abundance and stability of nodal phases is drastically affected by NH topology. While previous work has mostly considered complex degeneracies known as exceptional points as the NH counterpart of nodal points, we propose to relax this assumption by only requiring a crossing of the real part of the complex quasiparticle spectra, which entails a band crossing in the spectral function, i.e. a nodal spectral function. Interestingly, such real crossings are topologically protected by the braiding properties of the complex Bloch bands, and thus generically occur already in one-dimensional systems without symmetry or fine-tuning. We propose and study a microscopic lattice model in which a sublattice-dependent interaction stabilizes nodal spectral functions. Besides the gapless spectrum, we identify non-reciprocal charge transport properties after a local potential quench as a key signature of non-trivial band braiding. Finally, in the limit of zero interaction on one of the sublattices, we find a perfectly ballistic unidirectional mode in a non-integrable environment, reminiscent of a chiral edge state known from quantum Hall phases. Our analysis is corroborated by numerical simulations both in the framework of exact diagonalization and within the conserving second Born approximation.

[30]  arXiv:2405.05323 (cross-list from cond-mat.str-el) [pdf, other]

Title: Higher Berry Curvature from the Wave function II: Locally Parameterized States Beyond One Dimension

Authors: Ophelia Evelyn Sommer, Ashvin Vishwanath, Xueda Wen

Comments: 18 pages, 4 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)

We propose a systematic wave function based approach to construct topological invariants for families of lattice systems that are short-range entangled using local parameter spaces. This construction is particularly suitable when given a family of tensor networks that can be viewed as the ground states of $d$ dimensional lattice systems, for which we construct the closed $(d+2)$-form higher Berry curvature, which is a generalization of the well known 2-form Berry curvature. Such $(d+2)$-form higher Berry curvature characterizes a flow of $(d+1)$-form higher Berry curvature in the system. Our construction is equally suitable for constructing other higher pumps, such as the (higher) Thouless pump in the presence of a global on-site $U(1)$ symmetry, which corresponds to a closed $d$-form. The cohomology classes of such higher differential forms are topological invariants and are expected to be quantized for short-range entangled states. We illustrate our construction with exactly solvable lattice models that are in nontrivial higher Berry classes in $d=2$.

[31]  arXiv:2405.05325 (cross-list from cond-mat.str-el) [pdf, other]

Title: Higher Berry Phase from Projected Entangled Pair States in (2+1) dimensions

Authors: Shuhei Ohyama, Shinsei Ryu

Comments: 31pages, 10 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph); Quantum Physics (quant-ph)

We consider families of invertible many-body quantum states in $d$ spatial dimensions that are parameterized over some parameter space $X$. The space of such families is expected to have topologically distinct sectors classified by the cohomology group $\mathrm{H}^{d+2}(X;\mathbb{Z})$. These topological sectors are distinguished by a topological invariant built from a generalization of the Berry phase, called the higher Berry phase. In the previous work, we introduced a generalized inner product for three one-dimensional many-body quantum states, (``triple inner product''). The higher Berry phase for one-dimensional invertible states can be introduced through the triple inner product and furthermore the topological invariant, which takes its value in $\mathrm{H}^{3}(X;\mathbb{Z})$, can be extracted. In this paper, we introduce an inner product of four two-dimensional invertible quantum many-body states. We use it to measure the topological nontriviality of parameterized families of 2d invertible states. In particular, we define a topological invariant of such families that takes values in $\mathrm{H}^{4}(X;\mathbb{Z})$. Our formalism uses projected entangled pair states (PEPS). We also construct a specific example of non-trivial parameterized families of 2d invertible states parameterized over $\mathbb{R}P^4$ and demonstrate the use of our formula. Applications for symmetry-protected topological phases are also discussed.

[32]  arXiv:2405.05327 (cross-list from cond-mat.str-el) [pdf, other]

Title: Higher Berry Connection for Matrix Product States

Authors: Shuhei Ohyama, Shinsei Ryu

Comments: 34 pages, 6 figures

Subjects: Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph); Quantum Physics (quant-ph)

In one spatial dimension, families of short-range entangled many-body quantum states, parameterized over some parameter space, can be topologically distinguished and classified by topological invariants built from the higher Berry phase -- a many-body generalization of the Berry phase. Previous works identified the underlying mathematical structure (the gerbe structure) and introduced a multi-wavefunction overlap, a generalization of the inner product in quantum mechanics, which allows for the extraction of the higher Berry phase and topological invariants. In this paper, building on these works, we introduce a connection, the higher Berry connection, for a family of parameterized Matrix Product States (MPS) over a parameter space. We demonstrate the use of our formula for simple non-trivial models.

[33]  arXiv:2405.05440 (cross-list from physics.chem-ph) [pdf, other]

Title: Unbiasing Fermionic Auxiliary-Field Quantum Monte Carlo with Matrix Product State Trial Wavefunctions

Authors: Tong Jiang, Bryan O'Gorman, Ankit Mahajan, Joonho Lee

Comments: 24 pages, 20 figures

Subjects: Chemical Physics (physics.chem-ph); Quantum Physics (quant-ph)

In this work, we report, for the first time, an implementation of fermionic auxiliary-field quantum Monte Carlo (AFQMC) using matrix product state (MPS) trial wavefunctions, dubbed MPS-AFQMC. Calculating overlaps between an MPS trial and arbitrary Slater determinants up to a multiplicative error, a crucial subroutine in MPS-AFQMC, is proven to be #P-hard. Nonetheless, we tested several promising heuristics in successfully improving fermionic phaseless AFQMC energies. We also proposed a way to evaluate local energy and force bias evaluations free of matrix-product operators. This allows for larger basis set calculations without significant overhead. We showcase the utility of our approach on one- and two-dimensional hydrogen lattices, even when the MPS trial itself struggles to obtain high accuracy. Our work offers a new set of tools that can solve currently challenging electronic structure problems with future improvements.

[34]  arXiv:2405.05505 (cross-list from cond-mat.mes-hall) [pdf, other]

Title: Unveiling Higher-Order Topology via Polarized Topological Charges

Authors: Wei Jia, Bao-Zong Wang, Ming-Jian Gao, Jun-Hong An

Comments: 7+8 pages, 4+3 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Other Condensed Matter (cond-mat.other); Quantum Gases (cond-mat.quant-gas); Quantum Physics (quant-ph)

Real-space topological invariants were widely used to characterize chiral-symmetric higher-order topological phases (HOTPs). However, a momentum-space characterization to these HOTPs, which essentially reveals their intrinsic bulk-boundary correspondence and facilitates their detection in quantum simulation systems, is still lacking. Here, we propose an experimentally observable momentum-space characterization to the chiral-symmetric HOTPs by the concept of polarized topological charges. It makes a unified description to the HOTPs caused by the closing and reopening of band gap not only of the bulk states but also the edge states. Remarkably, these polarized topological charges can also be identified by measuring the pseudospin structures. A feasible scheme to detect the HOTPs in the $^{87}$Rb atomic system is given. Our work opens an avenue for characterization and experimental detection of the HOTPs in momentum space.

[35]  arXiv:2405.05528 (cross-list from physics.ed-ph) [pdf, ps, other]

Title: Spin(ing) into the classroom: Quantum spin activities for Year 6-10 physics

Authors: Kyla Adams, Anastasia Lonshakova, David Blair, David Treagust, Tejinder Kaur

Comments: 10 pages, 6 figures, 2 tables. Accepted for publication in Teaching Science

Subjects: Physics Education (physics.ed-ph); Quantum Physics (quant-ph)

Quantum science is in the news daily and engages student interest and curiosity. A fundamental quantum science concept that underpins medical imaging, quantum computing and many future technologies is quantum spin. Quantum spin can explain many physical phenomena that are in the lower secondary school curriculum, such as magnetism and light, making its inclusion a great motivator for students. Here we present an activity sequence for teaching quantum spin in the classroom using spinning tops and gyroscopes to highlight the common properties of classical angular momentum and quantum spin. These toys can provide an easily understood window to the quantum world for lower secondary school students. Students who have engaged in these activities reported enjoying the content and appreciating its relevance.

[36]  arXiv:2405.05603 (cross-list from math-ph) [pdf, ps, other]

Title: Twisting factors and fixed-time models in quantum field theory

Authors: Ezio Vasselli

Subjects: Mathematical Physics (math-ph); Quantum Physics (quant-ph)

We construct a class of fixed-time models in which the commutations relations of a Dirac field with a bosonic field are non-trivial and depend on the choice of a given distribution ("twisting factor"). If the twisting factor is fundamental solution of a differential operator, then applying the differential operator to the bosonic field yields a generator of the local gauge transformations of the Dirac field. Charged vectors generated by the Dirac field define states of the bosonic field which in general are not local excitations of the given reference state. The Hamiltonian density of the bosonic field presents a non-trivial interaction term: besides creating and annihilating bosons, it acts on momenta of fermionic wave functions. When the twisting factor is the Coulomb potential, the bosonic field contributes to the divergence of an electric field and its Laplacian generates local gauge transformations of the Dirac field. In this way we get a fixed-time model fulfilling the equal time commutation relations of the interacting Coulomb gauge.

[37]  arXiv:2405.05637 (cross-list from cond-mat.mes-hall) [pdf, other]

Title: Thermal junctions controlled with magnetic phases

Authors: José Balduque, Adrián Mecha, Rafael Sánchez

Comments: 12 pages, 13 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Physics (quant-ph)

Unlike charge, heat flows are difficult to control. We show that, in mesoscopic conductors, electronic thermal currents can be manipulated with a magnetic field by using the Aharonov-Bohm effect: the magnetic control of the interference pattern enhances the thermoelectric effect, while heat transport can be totally suppressed. In a three-terminal configuration, the flux-induced broken reciprocity generates a non-local thermoelectric response and translates to the circulation of heat. This way, efficient thermoelectric generators, thermal switches and thermal circulators, as well as energy harvesters can be defined for minimally disturbing thermal management at the nanoscale.

[38]  arXiv:2405.05671 (cross-list from cond-mat.mes-hall) [pdf, other]

Title: Self-correcting GKP qubit and gates in a driven-dissipative circuit

Authors: Frederik Nathan, Liam O'Brien, Kyungjoo Noh, Matthew H. Matheny, Arne L. Grimsmo, Liang Jiang, Gil Refael

Comments: 12 pages + 8 figures in the main text

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Physics (quant-ph)

We propose a circuit architecture for a dissipatively error-corrected GKP qubit. The device consists of a high-impedance LC circuit coupled to a Josephson junction and a resistor via a controllable switch. When the switch is activated via a particular family of stepwise protocols, the resistor absorbs all noise-induced entropy, resulting in dissipative error correction of both phase and amplitude errors. This leads to an exponential increase of qubit lifetime, reaching beyond 10ms in simulations with near-feasible parameters. We show that the lifetime remains exponentially long in the presence of extrinsic noise and device/control imperfections (e.g., due to parasitics and finite control bandwidth) under specific thresholds. In this regime, lifetime is likely only limited by phase slips and quasiparticle tunneling. We show that the qubit can be read out and initialized via measurement of the supercurrent in the Josephson junction. We finally show that the qubit supports native self-correcting single-qubit Clifford gates, where dissipative error-correction of control noise leads to exponential suppression of gate infidelity.

[39]  arXiv:2405.05783 (cross-list from nlin.CD) [pdf, other]

Title: Intermediate spectral statistics of rational triangular quantum billiards

Authors: Črt Lozej, Eugene Bogomolny

Comments: 14 pages, 11 figures

Subjects: Chaotic Dynamics (nlin.CD); Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)

Triangular billiards whose angles are rational multiples of $\pi$ are one of the simplest examples of pseudo-integrable models with intriguing classical and quantum properties. We perform an extensive numerical study of spectral statistics of eight quantized rational triangles, six belonging to the family of right-angled Veech triangles and two obtuse rational triangles. Large spectral samples of up to one million energy levels were calculated for each triangle which permits to determine their spectral statistics with great accuracy. It is demonstrated that they are of the intermediate type, sharing some features with chaotic systems, like level repulsion and some with integrable systems, like exponential tails of the level spacing distributions. Another distinctive feature of intermediate spectral statistics is a finite value of the level compressibility.
The short range statistics such as the level spacing distributions, and long-range statistics such as the number variance and spectral form factors were analyzed in detail. An excellent agreement between the numerical data and the model of gamma distributions is revealed.

Replacements for Fri, 10 May 24

[40]  arXiv:2106.11840 (replaced) [pdf, other]

Title: Quantum Computing -- A new scientific revolution in the making

Authors: Koen Bertels, Emma Turki, Tamara Sarac, Aritra Sarkar, Imran Ashraf

Comments: 16 pages, 5 figures

Subjects: Quantum Physics (quant-ph); Hardware Architecture (cs.AR)

[41]  arXiv:2209.13383 (replaced) [pdf, other]

Title: Signatures of quantum geometry from exponential corrections to the black hole entropy

Authors: Soham Sen, Ashis Saha, Sunandan Gangopadhyay

Comments: 16 pages LATEX

Journal-ref: Gen. Relativ. Gravit. 56 (2024) 57

Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)

[42]  arXiv:2211.06497 (replaced) [pdf, other]

Title: Generating $k$ EPR-pairs from an $n$-party resource state

Authors: Sergey Bravyi, Yash Sharma, Mario Szegedy, Ronald de Wolf

Comments: 35 pages, 5 figures. Quantum journal submission. DOI links for all references

Subjects: Quantum Physics (quant-ph)

[43]  arXiv:2304.05748 (replaced) [pdf, ps, other]

Title: Breaking and resurgence of symmetry in the non-Hermitian Su-Schrieffer-Heeger model in photonic waveguides

Authors: E. Slootman, W. Cherifi, L. Eek, R. Arouca, E. J. Bergholtz, M. Bourennane, C. Morais Smith

Comments: 24 pages, 17 figures

Journal-ref: Phys. Rev. Research 6, 023140 (2024)

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Optics (physics.optics); Quantum Physics (quant-ph)

[44]  arXiv:2306.05625 (replaced) [pdf, other]

Title: Kerr-effect-based quantum logical gates in decoherence-free subspace

Authors: Fang-Fang Du, Gang Fan, Xue-Mei Ren

Comments: 17 pages, 16 figures

Subjects: Quantum Physics (quant-ph)

[45]  arXiv:2306.10000 (replaced) [pdf, other]

Title: Loss-induced universal one-way transport in periodically driven systems

Authors: Chang Shu, Kai Zhang, Kai Sun

Comments: 14 pages, 14 figures

Journal-ref: Phys. Rev. B 109, 184302 (2024)

Subjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

[46]  arXiv:2306.13046 (replaced) [pdf, other]

Title: Practical limitations of quantum data propagation on noisy quantum processors

Authors: Gaurav Saxena, Ahmed Shalabi, Thi Ha Kyaw

Comments: 6+10 pages, 6 figures. Final version published in Physical Review Applied

Journal-ref: Phys. Rev. Applied 21, 054014 (2024)

Subjects: Quantum Physics (quant-ph)

[47]  arXiv:2306.14965 (replaced) [pdf, other]

Title: Renormalization Group Analysis of the Anderson Model on Random Regular Graphs

Authors: Carlo Vanoni, Boris L. Altshuler, Vladimir E. Kravtsov, Antonello Scardicchio

Comments: 8+6 pages, 3+7 figures, comments are welcome

Subjects: Disordered Systems and Neural Networks (cond-mat.dis-nn); Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)

[48]  arXiv:2307.10358 (replaced) [pdf, other]

Title: Virtual mitigation of coherent non-adiabatic transitions by echo verification

Authors: Benjamin F. Schiffer, Dyon van Vreumingen, Jordi Tura, Stefano Polla

Comments: 8+6 pages, 3+1 figures, accepted version

Subjects: Quantum Physics (quant-ph)

[49]  arXiv:2308.01073 (replaced) [pdf, other]

Title: Many-Body Mobility Edge in Quantum Sun models

Authors: Konrad Pawlik, Piotr Sierant, Lev Vidmar, Jakub Zakrzewski

Comments: 4pp+suppl, version close to accepted in PRB Lett

Subjects: Disordered Systems and Neural Networks (cond-mat.dis-nn); Quantum Gases (cond-mat.quant-gas); Quantum Physics (quant-ph)

[50]  arXiv:2308.01392 (replaced) [pdf, other]

Title: Quantum Classical Algorithm for the Study of Phase Transitions in the Hubbard Model via Dynamical Mean-Field Theory

Authors: Anshumitra Baul, Herbert F Fotso, Hanna Terletska, Juana Moreno, Ka-Ming Tam

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)

[51]  arXiv:2309.03983 (replaced) [pdf, other]

Title: Accurate Hyperfine Tensors for Solid State Quantum Applications: Case of the NV Center in Diamond

Authors: István Takács, Viktor Ivády

Subjects: Quantum Physics (quant-ph); Materials Science (cond-mat.mtrl-sci)

[52]  arXiv:2309.13232 (replaced) [pdf, ps, other]

Title: Semiquantum private comparison via cavity QED

Authors: Xin Xu, Jiang-Yuan Lian, Tian-Yu Ye

Comments: 21 pages, 7 figures, 2 tables

Journal-ref: Quantum Information Processing, 2024, 23: 174

Subjects: Quantum Physics (quant-ph)

[53]  arXiv:2310.06049 (replaced) [pdf, other]

Title: Quantum Illumination and Quantum Radar: A Brief Overview

Authors: Athena Karsa, Alasdair Fletcher, Gaetana Spedalieri, Stefano Pirandola

Subjects: Quantum Physics (quant-ph); Applied Physics (physics.app-ph); Data Analysis, Statistics and Probability (physics.data-an); Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)

[54]  arXiv:2310.11948 (replaced) [pdf, other]

Title: Robustness of the projected squeezed state protocol

Authors: B. J. Alexander, J. J. Bollinger, M. S. Tame

Comments: 19 pages, 12 figures, appendix

Subjects: Quantum Physics (quant-ph)

[55]  arXiv:2311.03647 (replaced) [pdf, ps, other]

Title: An algebraic formulation of nonassociative quantum mechanics

Authors: Peter Schupp, Richard J. Szabo

Comments: 35 pages; v2: minor corrections; v3: minor changes, Conclusions section added; Final version to appear in Journal of Physics A

Subjects: Quantum Physics (quant-ph); High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph); Rings and Algebras (math.RA)

[56]  arXiv:2311.08463 (replaced) [pdf, other]

Title: Magic in generalized Rokhsar-Kivelson wavefunctions

Authors: Poetri Sonya Tarabunga, Claudio Castelnovo

Comments: 19 pages,10 figures

Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el)

[57]  arXiv:2312.02743 (replaced) [pdf, other]

Title: Updating Bohr's Complementarity Principle

Authors: Diego S. Starke, Marcos L. W. Basso, Jonas Maziero

Subjects: Quantum Physics (quant-ph)

[58]  arXiv:2312.11597 (replaced) [pdf, other]

Title: Reinforcement Learning Based Quantum Circuit Optimization via ZX-Calculus

Authors: Jordi Riu, Jan Nogué, Gerard Vilaplana, Artur Garcia-Saez, Marta P. Estarellas

Comments: 15 pages, 10 figures

Subjects: Quantum Physics (quant-ph)

[59]  arXiv:2312.13473 (replaced) [pdf, other]

Title: Accuracy vs Memory Advantage in the Quantum Simulation of Stochastic Processes

Authors: Leonardo Banchi

Journal-ref: Machine Learning: Science and Technology, 5 025036, (2024)

Subjects: Quantum Physics (quant-ph); Information Retrieval (cs.IR); Machine Learning (cs.LG); Mathematical Physics (math-ph)

[60]  arXiv:2401.01671 (replaced) [pdf, other]

Title: Two-Unitary Complex Hadamard Matrices of Order $36$

Authors: Wojciech Bruzda, Karol Życzkowski

Comments: 13 pages, 1 figure

Subjects: Quantum Physics (quant-ph)

[61]  arXiv:2401.09027 (replaced) [pdf, ps, other]

Title: Exact Homomorphic Encryption

Authors: Zheng-Yao Su, Ming-Chung Tsai

Subjects: Quantum Physics (quant-ph); Cryptography and Security (cs.CR)

[62]  arXiv:2401.14368 (replaced) [pdf, other]

Title: Spectral gaps of two- and three-dimensional many-body quantum systems in the thermodynamic limit

Authors: Illya V. Lukin, Andrii G. Sotnikov, Jacob M. Leamer, Alicia B. Magann, Denys I. Bondar

Comments: 1D Haldane chain model analyzed (7 pages and 5 figures)

Journal-ref: Phys. Rev. Research 6, 023128 (2024)

Subjects: Quantum Physics (quant-ph); Strongly Correlated Electrons (cond-mat.str-el)

[63]  arXiv:2402.04705 (replaced) [pdf, other]

Title: Decoherence rate in random Lindblad dynamics

Authors: Yifeng Yang, Zhenyu Xu, Adolfo del Campo

Comments: 13 pages, 6 figures. Accepted for publication in Physical Review Research

Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics - Theory (hep-th)

[64]  arXiv:2402.15686 (replaced) [pdf, other]

Title: Lower bounds for quantum-inspired classical algorithms via communication complexity

Authors: Nikhil S. Mande, Changpeng Shao

Comments: 23 pages, the paper is modified to make the results more clear

Subjects: Quantum Physics (quant-ph); Computational Complexity (cs.CC)

[65]  arXiv:2403.02763 (replaced) [pdf, other]

Title: Quantum Zeno Monte Carlo for computing observables

Authors: Mancheon Han, Hyowon Park, Sangkook Choi

Comments: 15 figures

Subjects: Quantum Physics (quant-ph); Strongly Correlated Electrons (cond-mat.str-el)

[66]  arXiv:2403.05528 (replaced) [pdf, other]

Title: Systematic analysis of relative phase extraction in one-dimensional Bose gases interferometry

Authors: Taufiq Murtadho, Marek Gluza, Khatee Zathul Arifa, Sebastian Erne, Jörg Schmiedmayer, Nelly H.Y. Ng

Comments: Significant updates from v1, contains new results section on the effect of image processing, 21+12 pages, 22 figures

Subjects: Quantum Gases (cond-mat.quant-gas); Quantum Physics (quant-ph)

[67]  arXiv:2403.08496 (replaced) [pdf, other]

Title: Universal and robust quantum coherent control based on a chirped-pulse driving protocol

Authors: Yue-Hao Yin, Jin-Xin Yang, Li-Xiang Cen

Comments: 6 pages, 3 figures

Journal-ref: Phys. Rev. A 109, 042430 (2024)

Subjects: Quantum Physics (quant-ph)

[68]  arXiv:2403.08859 (replaced) [pdf, other]

Title: Solving lattice gauge theories using the quantum Krylov algorithm and qubitization

Authors: Lewis W. Anderson, Martin Kiffner, Tom O'Leary, Jason Crain, Dieter Jaksch

Comments: 19+19 pages, 7+4 figures, 0+5 tables. Fix typos, update format

Subjects: Quantum Physics (quant-ph); High Energy Physics - Lattice (hep-lat); High Energy Physics - Theory (hep-th)

[69]  arXiv:2403.12575 (replaced) [pdf, ps, other]

Title: Exact model reduction for discrete-time conditional quantum dynamics

Authors: Tommaso Grigoletto, Francesco Ticozzi

Subjects: Quantum Physics (quant-ph); Systems and Control (eess.SY)

[70]  arXiv:2404.14784 (replaced) [pdf, other]

Title: Hamiltonian simulation of minimal holographic sparsified SYK model

Authors: Raghav G. Jha

Comments: v2: Gate costs for up to 125 qubit-Hamiltonian i.e., N=250. 7 pages. Added few references, refined text. Comments welcome

Subjects: Quantum Physics (quant-ph); High Energy Physics - Lattice (hep-lat); High Energy Physics - Theory (hep-th)

[71]  arXiv:2404.15964 (replaced) [pdf, ps, other]

Title: Complex Stochastic Optimal Control Foundation of Quantum Mechanics

Authors: Vasil Yordanov

Subjects: Quantum Physics (quant-ph); Mathematical Physics (math-ph)

[72]  arXiv:2404.18616 (replaced) [pdf, other]

Title: Nonlinear Superconducting Magnetoelectric Effect

Authors: Jin-Xin Hu, Oles Matsyshyn, Justin C. W. Song

Comments: 6 pages, 3 figures, plus Supplementary

Subjects: Superconductivity (cond-mat.supr-con); Quantum Physics (quant-ph)

[73]  arXiv:2404.19554 (replaced) [pdf, other]

Title: Entanglement-assisted phase estimation algorithm for calculating dynamical response functions

Authors: Rei Sakuma, Shu Kanno, Kenji Sugisaki, Takashi Abe, Naoki Yamamoto

Subjects: Quantum Physics (quant-ph)

[74]  arXiv:2405.02630 (replaced) [pdf, other]

Title: cuTN-QSVM: cuTensorNet-accelerated Quantum Support Vector Machine with cuQuantum SDK

Authors: Kuan-Cheng Chen, Tai-Yue Li, Yun-Yuan Wang, Simon See, Chun-Chieh Wang, Robert Wille, Nan-Yow Chen, An-Cheng Yang, Chun-Yu Lin

Comments: 10 pages, 14 figures

Subjects: Quantum Physics (quant-ph); Distributed, Parallel, and Cluster Computing (cs.DC); Software Engineering (cs.SE)

• New submissions
• Cross-lists
• Replacements