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We report on a stringent test of the non-classicality of the motion of a massive quantum particle, which propagates on a discrete lattice. Measuring temporal correlations of the position of single atoms performing a quantum walk, we observe…

Quantum Physics · Physics 2015-02-11 Carsten Robens , Wolfgang Alt , Dieter Meschede , Clive Emary , Andrea Alberti

We investigate the behavior of correlations dynamics in a dissipative gain-loss system. First, we consider a setup made of two coupled lossy oscillators, with one of them subject to a local gain. This provides a more realistic platform to…

Quantum Physics · Physics 2023-05-24 Federico Roccati , Archak Purkayastha , G. Massimo Palma , Francesco Ciccarello

We consider a macroscopic quantum system in a tilted double-well potential. By solving Hamiltonian equation, we obtain tunneling probabilities which contain oscillation effects. To show how one can decide between quantum mechanics and the…

Quantum Physics · Physics 2018-08-02 Nasim Shahmansoori , Afshin Shafiee

The exceptional point has presented considerably interesting and counterintuitive phenomena associated with nonreciprocity, precision measurement, and topological dynamics. The Liouvillian exceptional point (LEP), involving the interplay of…

In the Leggett-Garg approach to testing macrorealism, the two-time correlation functions, which are normally obtained by sequential measurements of a dichotomic variable Q, need to be measured in a non-invasive way in order to exclude…

Quantum Physics · Physics 2016-11-23 J. J. Halliwell

Dynamical quantum phase transitions (DQPTs), which refer to the criticality in time of a quantum many-body system, have attracted much theoretical and experimental research interest recently. Despite DQPTs are defined and signalled by the…

Strongly Correlated Electrons · Physics 2021-08-11 Wing Chi Yu , P. D. Sacramento , Yan Chao Li , Hai-Qing Lin

Leggett-Garg inequalities are tests of macroscopic realism that can be violated by quantum mechanics. In this letter, we realise photonic Leggett-Garg tests on a three-level system and implement measurements that admit three distinct…

Quantum Physics · Physics 2018-02-05 Kunkun Wang , Clive Emary , Xiang Zhan , Zhihao Bian , Jian Li , Peng Xue

Despite the great success of quantum mechanics, questions regarding its application still exist and the boundary between quantum and classical mechanics remains unclear. Based on the philosophical assumptions of macrorealism and noninvasive…

Quantum Physics · Physics 2012-04-24 Jin-Shi Xu , Chuan-Feng Li , Xu-Bo Zou , Guang-Can Guo

We investigate the decay of spatial correlations of $\mathcal{PT}$-symmetric non-Hermitian one-dimensional models that host higher-order exceptional points. Beyond a certain correlation length, they develop anomalous power-law behavior that…

Mesoscale and Nanoscale Physics · Physics 2023-08-16 Doru Sticlet , Cătălin Paşcu Moca , Balázs Dóra

We study the dynamics of a driven non-Hermitian superconducting qubit which is perturbed by quantum jumps between energy levels, a purely quantum effect with no classical correspondence. The quantum jumps mix the qubit states leading to…

Quantum Physics · Physics 2021-10-05 Weijian Chen , Maryam Abbasi , Yogesh N. Joglekar , Kater W. Murch

Leggett and Garg formulated macrorealist models encoding our intuition on classical systems, i.e., physical quantities have a definite value that can be measured with minimal disturbance, and with the goal of testing macroscopic quantum…

Quantum Physics · Physics 2024-02-26 Giuseppe Vitagliano , Costantino Budroni

Recently defect production was investigated during non-unitary dynamics due to non-Hermitian Hamiltonian. By ramping up the non-Hermitian coupling linearly in time through an exceptional point, defects are produced in much the same way as…

Quantum Physics · Physics 2021-06-04 Balázs Gulácsi , Balázs Dóra

We investigate the intricate dynamics of quantum coherence and non-classical correlations in a two-qubit open quantum system coupled to a squeezed thermal reservoir. By exploring the correlations between spatially separated qubits, we…

Quantum Physics · Physics 2026-02-24 Neha Pathania , Ramniwas Meena , Subhashish Banerjee

The Leggett-Garg inequality (LGI) as a temporal analogue of Bell's inequality, derived using the notion of realism, is applied in a hitherto unexplored context involving the weak interaction induced two-state oscillations of decaying…

Quantum Physics · Physics 2015-06-15 D. Gangopadhyay , D. Home , A. Sinha Roy

We study the effects of dissipative boundaries in many-body systems at continuous quantum transitions, when the parameters of the Hamiltonian driving the unitary dynamics are close to their critical values. As paradigmatic models, we…

Statistical Mechanics · Physics 2021-09-01 Francesco Tarantelli , Ettore Vicari

We present a systematic investigation of particle number fluctuations in the crossover region near the critical endpoint of a first-order phase transition using molecular dynamics simulations of the classical Lennard-Jones fluid. We extend…

Quantum correlations are critical to our understanding of nature, with far-reaching technological and fundamental impact. These often manifest as violations of Bell's inequalities, bounds derived from the assumptions of locality and…

Temporal Bell inequalities, or Leggett-Garg Inequalities (LGI), are studied for continuous-variable systems placed in a squeezed state. The importance of those systems lies in their broad applicability which allows the description of many…

Quantum Physics · Physics 2021-07-19 Jerome Martin , Vincent Vennin

We study the macroscopic realism (macrorealism) through the two- and three-time Leggett-Garg inequalities (LGIs) in a two interacting qubits system. The two qubits are coupled either with two bosonic (thermal or photonic) baths or fermionic…

Quantum Physics · Physics 2020-05-26 Kun Zhang , Wei Wu , Jin Wang

Any pure state of a qubit can be geometrically represented as a point on the extended complex plane through stereographic projection. By employing successive conformal maps on the extended complex plane, we can generate an effective…

Quantum Physics · Physics 2026-04-20 Sourav Paul , Anant Vijay Varma , Sourin Das