Article
Physics, Multidisciplinary
Stanley S. Coelho, Lucas Queiroz, Danilo T. Alves
Summary: This article investigates the dynamics of harmonic oscillators with abrupt frequency jumps and presents expressions for energy, excitations, and transition probabilities using the Lewis-Riesenfeld method. The findings demonstrate that even with lower frequency jumps, the average energy of the oscillator remains equal to or greater than before the jumps.
Article
Astronomy & Astrophysics
Dimitris Moustos
Summary: In this study, we consider an Unruh-DeWitt detector modeled as a harmonic oscillator coupled to a massless quantum scalar field in (2+1)-dimensional Minkowski spacetime. We find that the dissipation rate and frequency shift of the accelerated detector depend on the acceleration temperature, which is contrary to the cases of inertial motion in a heat bath and other analogous quantum Brownian motion models in open systems.
Article
Mechanics
Giorgos Kanellopoulos, Dimitrios Razis, Ko van der Weele
Summary: In this paper, jumps in granular chute flow are obtained as continuous solutions of the Saint-Venant equations. The internal structure of these jumps is elucidated through a dynamical systems approach, showing trajectories organized around the stable/unstable manifold of a fixed point. An analytic approximate expression for jump length is derived, with numerical experiments confirming jump stability.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Astronomy & Astrophysics
Stephen L. Adler
Summary: In this study, we combine the concepts of a Weyl scaling invariant dark energy action and the gravastar theory. By utilizing the Tolman-Oppenheimer-Volkoff equation, we investigate the structure and dynamics of gravastars. Our Mathematica notebooks demonstrate that the structural changes of gravastars are determined by the action and equation of state, and the radii at which these changes occur are not predetermined. Additionally, we calculate the effects of a very small black hole wind using a relativistic extension of standard pressure-driven isothermal stellar wind theory.
Article
Physics, Multidisciplinary
E. Fitzke, R. Krebs, Th Haase, M. Mengler, G. Alber, Th Walther
Summary: This study reports the first realization of time-dependent quantum detector tomography for commercially available InGaAs avalanche photo detectors. Compared to previous research, the study constructs a time-dependent POVM based on experimental measurements, revealing important information about the interior of the detector.
NEW JOURNAL OF PHYSICS
(2022)
Review
Physics, Multidisciplinary
Dariusz Chruscinski
Summary: Quantum dynamical maps are important for representing quantum evolutions mathematically, with positivity and trace-preservation being necessary requirements. Complete positivity is crucial for proper representation, while Markovian semigroups provide approximate descriptions. The concept of CP-divisibility is widely accepted as a proper definition of quantum Markovianity.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2022)
Article
Mechanics
Riccardo Marcaccioli, Jean-Philippe Bouchaud, Michael Benzaquen
Summary: By synchronizing a database of stock specific news with 5 years worth of order book data on 300 stocks, the study examines the different dynamical features of abnormal price movements following news releases and those arising spontaneously. The research finds that large volatility fluctuations induced by exogenous events occur abruptly and are followed by a decaying power-law relaxation, while endogenous price jumps are characterized by progressively accelerating growth of volatility, also followed by a power-law relaxation, but slower than for exogenous jumps. These findings are reminiscent of observations in other contexts such as Amazon book sales and YouTube views.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2022)
Article
Multidisciplinary Sciences
M. Kalka, B. J. Spisak, D. Wozniak, M. Woloszyn, D. Kolaczek
Summary: The phase-space approach based on the Wigner distribution function is used to study the quantum dynamics of the three families of the Schrodinger cat states. The influence of barrier parameters on the nonclassical properties of these states in the phase space is analyzed. The relation between the entropic measure resulting from the Wigner-Renyi entropy and the nonclassicality parameter is proven.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Multidisciplinary
Barbara Soda, Vivishek Sudhir, Achim Kempf
Summary: In addition to the Unruh effect, acceleration can induce transparency and stimulated Unruh effect in the quantum theory of the light-matter interaction. These new phenomena have the potential to be observed experimentally.
PHYSICAL REVIEW LETTERS
(2022)
Article
Astronomy & Astrophysics
J. Ambjorn, Z. Drogosz, A. Gorlich, J. Jurkiewicz
Summary: The study reveals that the geometry of a quantum universe with a four-torus topology consists of a small semiclassical toroidal bulk part surrounded by many outgrowths with almost spherical topologies, yet still quite fractal.
Article
Automation & Control Systems
Jun Moon
Summary: This paper considers the path-dependent stochastic optimal control problem for jump-diffusion models. It proves the dynamic programming principle of the value functional and introduces the path-dependent integro-type Hamilton-Jacobi-Bellman equation. The verification theorem is provided to obtain the sufficient condition for optimality. The explicit optimal solutions are obtained for specific problems using the verification theorem and solving the corresponding PIHJB equation.
IEEE TRANSACTIONS ON AUTOMATIC CONTROL
(2022)
Article
Optics
Jiaan Qi, Xiansong Xu, Dario Poletti, Hui Khoon Ng
Summary: Dynamical decoupling (DD) is a widely used error mitigation method that aims to eliminate slowly evolving noise in quantum systems using pulse sequences. However, in the presence of noisy pulses, DD does not always effectively mitigate errors. It only works when the noise introduced by imperfect DD pulses is not greater than the original background noise.
Article
Automation & Control Systems
Jasmina Dordevic, Bojana Jovanovic
Summary: In this paper, a delayed stochastic SLVIQR epidemic model is derived, which can be applied to model the new coronavirus COVID-19 after calibration. The model assumes that the transmission rate follows a mean-reverting Ornstain-Uhlenbeck process and considers two additional driving processes: a stationary Poisson point process and a continuous finite-state Markov chain. The existence and uniqueness of the positive global solution are proven for the constructed model. Sufficient conditions for disease extinction or persistence in the mean are established, and the model is shown to have a richer dynamic analysis compared to existing models. Numerical simulations are provided to illustrate the theoretical results.
JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS
(2023)
Article
Quantum Science & Technology
Si-ren Yang, Chang-shui Yu
Summary: In this paper, we investigate how to quantify dynamical quantum resources in the resource non-increasing framework, presenting two methods: distance measures and maximal increasing static resource. Using the quantification of dynamical total coherence as a demonstration, the distance-based measures are shown to have good operational interpretation and can be numerically calculated through semidefinite programming, while measures based on the maximal increasing static resource lead to analytical solutions.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Physics, Multidisciplinary
Andrea Pizzamiglio, Su Yeon Chang, Maria Bondani, Simone Montangero, Dario Gerace, Giuliano Benenti
Summary: Quantum computers can simulate complex quantum system properties, such as dynamical localization, which is important for evaluating advances in quantum hardware performance.
Article
Physics, Multidisciplinary
Leigh S. Martin, William P. Livingston, Shay Hacohen-Gourgy, Howard M. Wiseman, Irfan Siddiqi
Article
Physics, Multidisciplinary
Travis J. Baker, Seyed N. Saadatmand, Dominic W. Berry, Howard M. Wiseman
Summary: Research shows that for an ideal laser beam, coherence can be roughly considered as the number of photons emitted consecutively with the same phase. Using the matrix product states method, a model achieving this scaling is found, indicating it could be realized using circuit quantum electrodynamics.
Article
Physics, Multidisciplinary
Eric G. Cavalcanti, Howard M. Wiseman
Summary: This research provides a new formulation of the Local Friendliness no-go theorem based on fundamental causal principles, showing how it imposes stricter constraints on quantum reality than Bell's theorem. Quantum causal models are proposed as a way to maintain a peaceful coexistence between quantum mechanics and relativistic causality.
Review
Physics, Multidisciplinary
Areeya Chantasri, Ivonne Guevara, Kiarn T. Laverick, Howard M. Wiseman
Summary: Quantum state estimation for continuously monitored dynamical systems involves assigning a quantum state to an individual system based on continuous observations. By integrating past and future information, a framework for partially observed quantum systems with continuous monitoring was proposed, along with the definition of new cost functions and types of estimators to bridge existing approaches.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2021)
Article
Quantum Science & Technology
Antoine Tilloy, Howard M. Wiseman
Summary: Spontaneous collapse models and Bohmian mechanics are two different approaches to addressing the measurement problem in orthodox quantum mechanics. Collapse models modify predictions by adding noise to the Schrodinger equation, while Bohmian mechanics guides particles using the wave function. Interestingly, it has been shown that collapse models can be exactly reformulated as Bohmian theories through careful consideration of non-Markovian systems and their relationships to Bohmian mechanics.
Article
Physics, Multidisciplinary
Qiu-Cheng Song, Travis J. Baker, Howard M. Wiseman
Summary: The Einstein, Podolsky and Rosen (EPR) phenomenon refers to the ability of one party to steer the quantum system of another party into two distinct ensembles of pure states. This phenomenon can be demonstrated even with mixed states, as long as they are pure enough and different enough. Specifically, if the first measurement setting yields an ensemble comprising two pure states, EPR-steering can be shown with any other measurement setting.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
L. A. Ostrowski, T. J. Baker, S. N. Saadatmand, H. M. Wiseman
Summary: The Heisenberg limit restricts the laser coherence T, which is the number of photons in the most populated mode of the laser beam, to be proportional to the fourth power of the number of excitations inside the laser. We extend the previous proof of this upper bound scaling by relaxing the requirement of Poissonian photon statistics (i.e., Mandel's Q = 0). Furthermore, we demonstrate that the relationship between T and sub-Poissonianity (Q < 0) is win-win rather than a tradeoff. In both regular (non-Markovian) pumping with semiunitary gain (allowing Q -> -1) and random (Markovian) pumping with optimized gain, T is maximized when Q is minimized.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
L. A. Ostrowski, T. J. Baker, S. N. Saadatmand, H. M. Wiseman
Summary: Recently, a study has shown that a laser can produce a stationary beam with enhanced coherence by storing a higher number of excitations within the laser. This finding challenges the traditional limits of laser coherence and introduces new laser models with different parameterizations. The study also explores the influence of these parameters on the coherence and photon statistics of the laser beams, revealing distinct regimes based on the parameter values. The optimal parameter value is found to be approximately 4.15 instead of the conventional value of 4.
Article
Optics
Hongting Song, Areeya Chantasri, Behnam Tonekaboni, Howard M. Wiseman
Summary: Spectator qubits (SQs) are used to reduce noise in inaccessible data qubits. SQs, which are more sensitive to noise, are measured frequently and the results are rarely used to correct data qubits. A Bayesian method utilizing complex linear maps is introduced to address dephasing from random telegraph noise, which results in an optimally adaptive measurement and control protocol. The decoherence rate suppression is quadratic in the sensitivity of the SQ, demonstrating that the SQ paradigm works well in the appropriate regime.
Article
Quantum Science & Technology
Howard M. Wiseman, Aephraim M. Steinberg, Matin Hallaji
Summary: This article presents a method for measuring weak values using strong coherent states, eliminating the difficulties and slow rate associated with preparing single photons.
AVS QUANTUM SCIENCE
(2023)
Article
Optics
Qiu-Cheng Song, Travis J. Baker, Howard M. Wiseman
Summary: This study investigates quantum steering in a network scenario involving n parties, introducing different scenarios and analyzing the necessary steering criteria for different measurement settings. It finds that using a semi-random pair entanglement construction, one party can steer every other party for arbitrarily large n.
Correction
Optics
Kiarn T. Laverick, Ivonne Guevara, Howard M. Wiseman
Article
Optics
Kiarn T. Laverick, Ivonne Guevara, Howard M. Wiseman
Summary: Quantum state smoothing is a technique to estimate an unknown true state of an open quantum system based on partial measurement information both prior and posterior to the time of interest. The smoothed quantum state is an optimal Bayesian state estimator, minimizing a Bayesian expected cost function. It is optimal with respect to trace-square deviation from and relative entropy to the unknown true state, but not optimal with respect to linear infidelity. An optimal state estimator, the lustrated smoothed state, is derived for this case.
Article
Physics, Multidisciplinary
Kiarn T. Laverick, Areeya Chantasri, Howard M. Wiseman
Summary: Quantum state smoothing is a technique for estimating the quantum state of a partially observed quantum system, requiring the observer to understand unknown measurement records in order to obtain an accurate true state. Making incorrect assumptions may result in suboptimal or unrealizable smoothed states.
QUANTUM STUDIES-MATHEMATICS AND FOUNDATIONS
(2021)
Article
Optics
Kiarn T. Laverick, Areeya Chantasri, Howard M. Wiseman
Summary: Researchers have introduced a linear Gaussian quantum (LGQ) state smoothing technique and studied the impact of Bob's measurement choice on Alice's smoothing effectiveness, proposing a simple hypothesis for estimating Bob's optimal measurement choice.
