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We show that the spectral gap problem is undecidable. Specifically, we construct families of translationally-invariant, nearest-neighbour Hamiltonians on a 2D square lattice of d-level quantum systems (d constant), for which determining…

Quantum Physics · Physics 2022-07-28 Toby Cubitt , David Perez-Garcia , Michael M. Wolf

The shift of energy levels owing to broadband electromagnetic vacuum fluctuations, the Lamb shift, has been pivotal in the development of quantum electrodynamics and in understanding atomic spectra. Currently, small energy shifts in…

The presence of a dissipative environment disrupts the unitary spectrum of dynamical quantum maps. Nevertheless, key features of the underlying unitary dynamics -- such as their integrable or chaotic nature -- are not immediately erased by…

Eisenbud-Wigner-Smith delay and the Larmor time give different estimates for the duration of a quantum scattering event. The difference is most pronounced in the case where de-Broglie wavelength is large compared to the size of the…

Quantum Physics · Physics 2024-01-17 X. Gutiérrez de la Cal , M. Pons , D. Sokolovski

We study equilibration of an isolated quantum system by mapping it onto a network of classical oscillators in Hilbert space. By choosing a suitable basis for this mapping, the degree of locality of the quantum system reflects in the…

Quantum Physics · Physics 2019-05-14 Daniel Nickelsen , Michael Kastner

The dynamics of open quantum systems is formulated in a minimally extended state space comprising the degrees of freedom of a system of interest and a finite set of non-unitary, pure-state reservoir modes. This formal structure, derived…

Quantum Physics · Physics 2023-08-01 Meng Xu , Vasilii Vadimov , Malte Krug , J. T. Stockburger , J. Ankerhold

Given a multilevel system coupled to a bath, we use a Feshbach P,Q partitioning technique to derive an exact trace-nonpreserving master equation for a subspace $\mathcal{S}_{i}$ of the system. The resultant equation properly treats the…

Quantum Physics · Physics 2009-11-13 Lian-Ao Wu , Gershon Kurizki , Paul Brumer

Fluctuation Theorems are central in stochastic thermodynamics, as they allow for quantifying the irreversibility of single trajectories. Although they have been experimentally checked in the classical regime, a practical demonstration in…

Quantum Physics · Physics 2017-10-27 C. Elouard , N. K. Bernardes , A. R. R. Carvalho , M. F. Santos , A. Auffèves

We review our results for the dynamics of isolated many-body quantum systems described by one-dimensional spin-1/2 models. We explain how the evolution of these systems depends on the initial state and the strength of the perturbation that…

Statistical Mechanics · Physics 2017-08-03 Lea F. Santos , E. Jonathan Torres-Herrera

Large-scale quantum systems require optical coherence between distant quantum devices, necessitating spectral indistinguishability. Scalable solid-state platforms offer promising routes to this goal. However, environmental disorders,…

We provide bounds on temporal fluctuations around the infinite-time average of out-of-time-ordered and time-ordered correlators of many-body quantum systems without energy gap degeneracies. For physical initial states, our bounds predict…

Strongly Correlated Electrons · Physics 2023-12-20 Talía L. M. Lezama , Yevgeny Bar Lev , Lea F. Santos

We present a systematic method to implement a perturbative Hamiltonian diagonalization based on the time-dependent Schrieffer-Wolff transformation. Applying our method to strong parametric interactions we show how, even in the dispersive…

Quantum Physics · Physics 2022-08-08 Z. Xiao , E. Doucet , T. Noh , L. Ranzani , R. W. Simmonds , L. C. G. Govia , A. Kamal

By proposing a paradox between the impossibility of superluminal signal transfer and the normalization condition of wavefunctions, we predict that when a change happens to the conditions that determining the status of a quantum system, the…

Quantum Physics · Physics 2009-11-17 Guang Ping He

It is well known in quantum mechanics that a large energy gap between a Hilbert subspace of specific interest and the remainder of the spectrum can suppress transitions from the quantum states inside the subspace to those outside due to…

Quantum Physics · Physics 2020-05-29 Zongping Gong , Nobuyuki Yoshioka , Naoyuki Shibata , Ryusuke Hamazaki

We demonstrate that the dynamics of an open quantum system can be calculated efficiently and with predefined error, provided a basis exists in which the system-environment interactions are local and hence obey the Lieb-Robinson bound. We…

Quantum Physics · Physics 2015-03-19 Giulia Gualdi , Christiane P. Koch

We explore the Lyapunov spectrum and entanglement entropy in systems evolved by quantum measurements and spatially homogeneous unitary gates. In models with temporally random and Floquet unitary gates, we find that the Lyapunov exponents…

Quantum Physics · Physics 2025-07-16 Ken Mochizuki , Ryusuke Hamazaki

We consider a quantum particle coupled (with strength $\la$) to a spatial array of independent non-interacting reservoirs in thermal states (heat baths). Under the assumption that the reservoir correlations decay exponentially in time, we…

Mathematical Physics · Physics 2015-05-13 W. De Roeck , J. Frohlich , A. Pizzo

In this article we prove that for a large class of operators, including Schroedinger operators, with hyperbolic classical flows, the smallness of dimension of the trapped set implies that there is a gap between the resonances and the real…

Mathematical Physics · Physics 2007-08-13 Stephane Nonnenmacher , Maciej Zworski

The recent investigation into the phenomena of refraction and reflection at temporal boundaries, conducted through the lens of spacetime duality, has attracted considerable scholarly interest. This duality unveils insights into the…

Optics · Physics 2025-03-21 Jing Wang , Yuetao Chen , Shaoyan Gao

We demonstrate a surprising connection between pure steady state entanglement and relaxation timescales in an extremely broad class of Markovian open systems, where two (possibly many-body) systems $A$ and $B$ interact locally with a common…

Quantum Physics · Physics 2024-10-17 Andrew Pocklington , Aashish A. Clerk