Review
Physics, Multidisciplinary
Chandan Datta, Tulja Varun Kondra, Marek Miller, Alexander Streltsov
Summary: This article discusses the concept of catalysts and their applications in both chemistry and quantum fields. It focuses on the recent developments in quantum catalysis and the study of phenomena such as quantum entanglement, coherence, and thermodynamics.
REPORTS ON PROGRESS IN PHYSICS
(2023)
Article
Physics, Multidisciplinary
Mohamad Niknam, Lea F. Santos, David G. Cory
Summary: The research proposes and experimentally measures an entropy that quantifies correlations among qubits in a nearly isolated quantum system. Due to spin-spin interactions, information flows from a central spin to surrounding ones forming clusters of multispin correlations that grow over time. A nuclear magnetic resonance experiment is used to directly measure the amplitudes of multispin correlations and compute the evolution of what is called correlation Renyi entropy, which continues to grow even after the equilibration of entanglement entropy. The study also analyzes how the saturation point and timescale for the equilibration of the correlation Renyi entropy depend on the system size.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Mohammad Pouranvari, Shiuan-Fan Liou
Summary: In this study, characterizations of many-body phase transitions between delocalized and localized phases based on boundary conditions sensitivity were introduced. By numerically calculating shifts in the system's energy and single-particle density matrix eigenvalues, the vanishing shifts in the localized regime and order of level spacing shifts in the extended regime were observed. The characterizations were also applied to cases with next-nearest-neighbor interactions in addition to nearest-neighbor interactions to study the effect on the phase transition.
Article
Physics, Multidisciplinary
Katja Klobas, Bruno Bertini
Summary: We study the entanglement dynamics generated by quantum quenches in the quantum cellular automaton Rule 54. By considering the evolution from a recently introduced class of solvable initial states, we were able to characterize the thermalisation dynamics of local observables and derive exact formulas describing the asymptotic linear growth of all Renyi entropies in the thermodynamic limit and their eventual saturation for finite subsystems. Our results apply to both homogeneous and inhomogeneous quenches, with exact predictions for von Neumann entropy and no physically meaningful quasiparticle description for other Renyi entropies.
Article
Physics, Multidisciplinary
Hongzheng Zhao, Adam Smith, Florian Mintert, Johannes Knolle
Summary: This paragraph discusses quantum many-body scars as counterexamples to the eigenstate thermalization hypothesis, highlighting their atypical characteristics and related properties.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Lea Kraemer, Lidia del Rio
Summary: This study discusses how to quantify the value of physical resources and introduces a new method - currencies, to quantify the realistic descriptions of resources in experimental settings and derive the necessary conditions for resource conversion. By studying the description and conversion of resources, it generalizes axiomatic approaches to entropy, work, and currencies.
Article
Physics, Fluids & Plasmas
Lars Knipschild, Andreas Engel, Jochen Gemmer
Summary: This study examines closed quantum systems, driven with negligible heating effects, to determine the conditions under which the Jarzynski relation holds for microcanonical or energy eigenstates. The validity of the Jarzynski relation depends on the exponential density of states, stiffness, and smoothness, indicating the independence of work probability density functions on energy levels and specific energy eigenstates. The validity of the Jarzynski relation for pure energy eigenstates is considered a unique quantum phenomenon absent in classical systems.
Article
Physics, Multidisciplinary
Youssef Aziz Alaoui, Bihui Zhu, Sean Robert Muleady, William Dubosclard, Tommaso Roscilde, Ana Maria Rey, Bruno Laburthe-Tolra, Laurent Vernac
Summary: In this study, collective spin measurements are performed to investigate the development of two-body correlations between 104 spin s = 3 chromium atoms pinned in a 3D optical lattice. The interactions between spins are characterized by long range and anisotropic dipolar interactions. The fluctuations of total magnetization are measured to estimate the growth of connected pairwise correlations associated with magnetization, and the quantum nature of these correlations is assessed through comparisons with analytical expansions and numerical simulations.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Charis Anastopoulos, Bei-Lok Hu
Summary: The paper points out three common problems in using quantum information theory to address gravity-related issues, including the inconsistency between interactions mediated by an information channel and those treated by quantum field theory, the neglect of important quantum features when replacing a quantum field with a classical stochastic field, and the conditions under which semi-classical and stochastic theories can be formulated from their quantum origins.
Article
Mechanics
Ramanjit Sohal, Laimei Nie, Xiao-Qi Sun, Eduardo Fradkin
Summary: This article investigates the thermalization of Sachdev-Ye-Kitaev (SYK) models coupled via random interactions from the perspective of entanglement. The study shows that the thermalization behavior of SYK models coupled by two-body terms differs from those coupled by single-body terms.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2022)
Article
Physics, Multidisciplinary
Martin Alpert
Summary: A new quantum mechanics mechanism theory based on statistical mechanics is introduced in this article to explain the relationship between energy changes and state changes during the observation process. Two experiments are proposed to validate the theory and it is anticipated that the validation will further enhance the understanding of the measurement process and entanglement.
FRONTIERS IN PHYSICS
(2022)
Article
Physics, Multidisciplinary
Georgios Styliaris, Namit Anand, Paolo Zanardi
Summary: The study presents exact analytical results for the bipartite OTOC, showing its relationship with operator entanglement and its impact on entangling power. Additionally, it explores the connection between long-time averages of the OTOC and eigenstate entanglement.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
David Villasenor, Saul Pilatowsky-Cameo, Miguel A. Bastarrachea-Magnani, Sergio Lerma-Hernandez, Lea F. Santos, Jorge G. Hirsch
Summary: We analyze the relationship between chaos and thermalization onset in the spin-boson Dicke model. The eigenstate expectation values and distributions of off-diagonal elements validate the eigenstate thermalization hypothesis (ETH) in the chaotic region, indicating thermalization. The chaotic structure of the eigenstates is confirmed using von Neumann entanglement entropy and Shannon entropy.
Article
Materials Science, Multidisciplinary
Saranyo Moitra, Rajdeep Sensarma
Summary: This study provides a method to construct the Renyi and von Neumann entropy of a system of interacting fermions from its correlation functions. The Renyi entanglement entropy of interacting fermions in arbitrary dimensions can be represented by a Schwinger-Keldysh free energy on replicated manifolds with a current between the replicas. Using this representation, entanglement can be decomposed into contributions based on the one-particle correlator, two-particle correlator, etc. This construction is agnostic to the calculation method, allowing for the use of calculated, simulated, or measured values of the correlators.
Article
Materials Science, Multidisciplinary
Christopher M. Langlett, Shenglong Xu
Summary: This work introduces a family of spin-1/2 many-body Hamiltonians based on the Fredkin spin chain, featuring a fragmented Hilbert space and quantum many-body scars. Exact middle spectrum eigenstates are constructed to demonstrate logarithmic or area-law entanglement entropy within each fractured subsector. The interplay between fragmentation and scarring results in rich tunable nonergodic dynamics.
Article
Physics, Multidisciplinary
Simon Morelli, Hayata Yamasaki, Marcus Huber, Armin Tavakoli
Summary: This study investigates entanglement detection in scenarios where local measurements only nearly correspond to the intended measurements. The authors formalize this through an operational notion of inaccuracy that can be estimated directly in the lab. They demonstrate that small magnitudes of inaccuracy can significantly compromise well-known entanglement witnesses.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Zahra Baghali Khanian, Manabendra Nath Bera, Arnau Riera, Maciej Lewenstein, Andreas Winter
Summary: We extend the previous results on quantum thermodynamics to the case of multiple non-commuting charges and develop a resource theory of thermodynamics for asymptotically many non-interacting systems. The phase diagram of the system is formed by associating the vector of expected charge values and entropy with every state. Our key result is the Asymptotic Equivalence Theorem, which connects the equivalence classes of states under asymptotic charge-conserving unitaries with the points on the phase diagram. Using the phase diagram, we analyze the first and second laws of thermodynamics and provide insights into the storage of different charges in physically separate batteries.
ANNALES HENRI POINCARE
(2023)
Article
Multidisciplinary Sciences
Pavel Hrmo, Benjamin Wilhelm, Lukas Gerster, Martin W. van Mourik, Marcus Huber, Rainer Blatt, Philipp Schindler, Thomas Monz, Martin Ringbauer
Summary: Quantum information carriers naturally occupy high-dimensional Hilbert spaces, and high-dimensional (qudit) quantum systems are becoming a powerful resource for quantum processors. Generating the desired interaction efficiently in these systems is crucial. In this study, the authors demonstrate the implementation of a native two-qudit entangling gate up to dimension 5 in a trapped-ion system. They use a light-shift gate mechanism to generate genuine qudit entanglement in a single application of the gate, which seamlessly adapts to the local dimension of the system with a calibration overhead independent of the dimension. Native entangling techniques for qudits are important for encoding quantum information.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Lukas Bulla, Matej Pivoluska, Kristian Hjorth, Oskar Kohout, Jan Lang, Sebastian Ecker, Sebastian P. Neumann, Julius Bittermann, Robert Kindler, Marcus Huber, Martin Bohmann, Rupert Ursin
Summary: Entanglement distribution via photons over long distances enables many applications, including quantum key distribution. The degradation of entanglement remains a challenge due to noise accumulation. This study presents a long-range free-space quantum link that distributes entanglement over 10.2 km with flexible dimensionality of encoding. The approach utilizes high-dimensional entangled photons and analyzes the achievable key rate in a dimensionally adaptive quantum key distribution protocol.
Article
Quantum Science & Technology
Shuheng Liu, Qiongyi He, Marcus Huber, Otfried Guhne, Giuseppe Vitagliano
Summary: We propose a method to detect the dimensionality of entanglement using correlations between measurements in randomized directions. By deriving an inequality based on the covariance matrix criterion, which is invariant under local changes of su(d) bases, we can find regions in the space of randomized correlations moments that determine the different dimensionalities of entanglement. Our method shows promising results in practical scenarios and can detect more states than existing criteria, making it a powerful and potentially simpler approach. Future work should focus on implementing this method in multipartite scenarios.
Article
Quantum Science & Technology
Nathan Keenan, Niall F. Robertson, Tara Murphy, Sergiy Zhuk, John Goold
Summary: In this study, we digitally simulate the quantum dynamics of a spin-21 XXZ spin chain on a noisy near-term quantum device, and extract the high temperature transport exponent at the isotropic point. By simulating the temporal decay of the relevant spin correlation function using a pseudo-random state generated by a tailored random circuit on the ibmq-montreal 27 qubit device, we observe a spin excitation on a homogeneous background. The subsequent discrete time dynamics on the device reveal an anomalous super-diffusive exponent consistent with the conjectured Kardar-Parisi-Zhang (KPZ) scaling at the isotropic point. Furthermore, we restore spin diffusion by applying an integrability breaking potential.
NPJ QUANTUM INFORMATION
(2023)
Article
Optics
Lukas Bulla, Kristian Hjorth, Oskar Kohout, Jan Lang, Sebastian Ecker, Sebastian P. Neumann, Julius Bittermann, Robert Kindler, Marcus Huber, Martin Bohmann, Rupert Ursin, Matej Pivoluska
Summary: Our study investigates the presence of high-dimensional entanglement in a recent demonstration of a noise-resistant quantum key distribution (QKD) protocol. We found that the distributed entangled states can be certified to have at least three dimensions. To show this, we developed an energy-time entanglement discretization technique and an improved witness for entanglement dimensionality. Our results provide insight into the complex relationship between high-dimensional entanglement and the noise resistance of QKD protocols operating in high dimensions.
Article
Optics
Jake Xuereb, Steve Campbell, John Goold, Andre Xuereb
Summary: We examine the deterministic quantum computation with one-clean-qubit model (DQC1) complexity class as an open quantum system. We show that the evolution of the logical qubit in any algorithm in the complexity class can be described as an open quantum system undergoing unital dynamics. Unital quantum channels respect the Tasaki-Crooks fluctuation theorem, which is captured by the thermodynamics of the logical qubit. As an application, we investigate the equilibrium and nonequilibrium thermodynamics of the DQC1 trace estimation algorithm, revealing the impact of computational inputs and logical qubit temperature on the algorithm's quality and fluctuations experienced.
Article
Quantum Science & Technology
Archak Purkayastha, Giacomo Guarnieri, Steve Campbell, Javier Prior, John Goold
Summary: We introduce a unique class of cyclic quantum thermal machines (QTMs) that can maximize their performance at a finite cycle duration T where they are most irreversible. These QTMs can interpolate between standard collisional QTMs and autonomous QTMs operated by simultaneous coupling to multiple macroscopic baths. We discuss the physical realization of these processes and demonstrate that it requires a finite number of copies of the baths. The analysis also reveals interesting connections with Zeno and anti-Zeno effects.
Article
Physics, Fluids & Plasmas
Oisin Culhane, Mark T. Mitchison, John Goold
Summary: Recent experiments have shown the generation of coherent mechanical oscillations in a suspended carbon nanotube, similar to a lasing transition. In this study, we investigate this phenomenon from the perspective of work extraction, modeling a nanoelectromechanical device as a quantum flywheel or battery that converts electrical power into stored mechanical energy. By introducing a microscopic model that matches the experimental findings, we compute the Wigner function of the quantum vibrational mode in its nonequilibrium steady state. We utilize two approaches, ergotropy and nonequilibrium free energy, to characterize the threshold for self-sustained oscillations in nonequilibrium quantum thermodynamics. We find that ergotropy serves as an order parameter for the phonon lasing transition. The framework employed in this study can be generalized and applied to other mesoscopic quantum devices.
Article
Optics
Giacomo Guarnieri, Mark T. Mitchison, Archak Purkayastha, Dieter Jaksch, Berislav Buca, John Goold
Summary: Spontaneous periodic oscillation can emerge in the repeated-interaction description of open quantum systems, which is significant for implementing specific spin models in quantum simulators.
Article
Quantum Science & Technology
Andres F. Ducuara, Paul Skrzypczyk
Summary: This paper introduces operational quantum tasks called quantum betting tasks, which are based on risk aversion. The advantage of informative measurements in these tasks can be accurately characterized by Arimoto's alpha-mutual information. Furthermore, it is discovered that Arimoto-type information-theoretic quantities characterize the advantage that resourceful objects offer in quantum betting tasks compared to resourceless objects. New quantum Renyi divergences for measurements are also introduced, along with a new family of resource monotones for the measurement informativeness.
Article
Quantum Science & Technology
Eyuri Wakakuwa, Yoshifumi Nakata, Min-Hsiu Hsieh
Summary: This study investigates state redistribution of a hybrid information source that consists of both classical and quantum components. It explores the transmission of classical and quantum information simultaneously, using shared entanglement and noiseless classical and quantum communication channels. The study presents direct and converse bounds for these three resources based on the smooth conditional entropies of the source state. It also derives various coding theorems for two-party source coding problems, some of which have not been addressed in previous literature.
Article
Materials Science, Multidisciplinary
Cecilia Chiaracane, Archak Purkayastha, Mark T. Mitchison, John Goold
Summary: Understanding and controlling quantum transport in low-dimensional systems is crucial for heat management at the nanoscale. This study investigates the effect of quasiperiodic disorder, which induces fractality in the energy spectrum, on the thermal and electric conductivities of a noninteracting model. The research finds that the presence of dephasing noise enhances transport in the subdiffusive regime and leads to multiple peaks in both thermal and electric conductivities, violating the Wiedemann-Franz law. This feature can be utilized to enhance the performance of quantum thermal machines.
Article
Optics
Mark T. Mitchison, Archak Purkayastha, Marlon Brenes, Alessandro Silva, John Goold
Summary: This study proposes a scheme to measure the temperature of pure states through quantum interference, showing that even individual pure quantum states can have temperatures in completely isolated quantum systems.
