Research on the out-of-equilibrium dynamics of quantum systems has so far produced important statements thermodynamics small undergoing mechanical evolutions. Key examples are provided by Crooks and Jarzynski relations: taking into account fluctuations in non-equilibrium dynamics, such relations connect equilibrium properties thermodynamical relevance with explicit features. Although experimental verification fundamental classical domain encountered some success, their version requires...

By means of the time dependent density matrix renormalization group algorithm we study zero-temperature dynamics Von Neumann entropy a block spins in Heisenberg chain after sudden quench anisotropy parameter. In absence any disorder increases linearly with and then saturates. We analyse velocity propagation entanglement as function initial final anisotropies compare our results, wherever possible, those obtained by conformal field theory. disordered case find slower (logarithmic) evolution...

We propose an interferometric setting for the ancilla-assisted measurement of characteristic function work distribution following a time-dependent process experienced by quantum system. identify how configuration effective interferometer is linked to symmetries enjoyed Hamiltonian ruling and provide explicit form operations implement in order accomplish our task. finally discuss two physical settings, based on hybrid optomechanical-electromechanical devices, where theoretical proposals...

The study of open quantum systems often relies on approximate master equations derived under the assumptions weak coupling to environment. However when system is made several interacting subsystems such a derivation in many cases very hard. An alternative method, employed especially modelling transport mesoscopic systems, consists using {\it local} containing Lindblad operators acting locally only corresponding subsystem. It has been shown that this approach however generates inconsistencies...

The effect of fluctuations in the classical control parameters on Berry phase a spin 1/2 interacting with an adiabatically cyclically varying magnetic field is analyzed. It explicitly shown that adiabatic limit dephasing due to dynamical phase.

A chain of singly charged particles, confined by a harmonic potential, exhibits sudden transition to zigzag configuration when the radial potential reaches critical value, depending on particle number. This structural change is phase second order, whose order parameter crystal displacement from axis. We study analytically using Landau theory and find full agreement with numerical predictions Schiffer [Phys. Rev. Lett. 70, 818 (1993)] Piacente et al. B 69, 045324 (2004)]. Our allows us...

The nonequilibrium dynamics of an ion chain in a highly anisotropic trap is studied when the transverse frequency quenched across value at which undergoes continuous phase transition from linear to zigzag structure. Within Landau theory, equation for order parameter, corresponding size structure, determined vibrational motion damped via laser cooling. number structural defects produced during quench trapping predicted and verified numerically. It shown obey scaling by Kibble-Zurek mechanism,...

We investigate the entanglement spectrum near criticality in finite quantum spin chains. Using size scaling we show that when approaching a phase transition, Schmidt gap, i.e., difference between two largest eigenvalues of reduced density matrix, signals critical point and scales with universal exponents related to relevant operators corresponding perturbed conformal field theory describing point. Such behavior allows us identify explicitly gap as local order parameter.

We study quantum information flow in a model comprising of an impurity qubit immersed Bose-Einstein condensed reservoir. demonstrate how flux between the and condensate can be manipulated by engineering ultracold reservoir within experimentally realistic limits. place particular emphasis on non-Markovian dynamics, characterized reversed from background gas to identify controllable crossover Markovian dynamics parameter space model.

We study transitionless quantum driving in an infinite-range many-body system described by the Lipkin-Meshkov-Glick model. Despite correlation length being always infinite closing of gap at critical point makes Hamiltonian increasing complexity also this case. To aim we develop a hybrid strategy combining shortcut to adiabaticity and optimal control that allows us achieve remarkably good performance suppressing defect production across phase transition.

We introduce the idea of weakly coherent collisional models, where elements an environment interacting with a system interest are prepared in states that approximately thermal but have amount coherence proportional to short system-environment interaction time scenario akin well-known models. show that, continuous-time limit, model allows for clear formulation first and second laws thermodynamics, which modified include nontrivial contribution related quantum coherence. Remarkably, we derive...

Unitary processes allow for the transfer of work to and from Hamiltonian systems. However, achieve nonzero power practical extraction work, these must be performed within a finite time, which inevitably induces excitations in system. We show that depending on time scale process physical realization external driving employed, use counterdiabatic quantum extract more is not always effective. also by virtue two-time energy measurement definition cost can significantly reduced selecting...

We introduce the multipartite collision model, defined in terms of elementary interactions between subsystems and ancillas, show that it can simulate Markovian dynamics any open quantum system. develop a method to estimate an analytical error bound for repeated we use prove our scheme displays optimal scaling. Finally, provide simple decomposition model into gates, is efficiently simulable on computer according dissipative Church-Turing theorem, i.e., requires polynomial number resources.

We study the robustness of evolution a quantum system against small uncontrolled variations in parameters Hamiltonian. show that fidelity susceptibility, which quantifies perturbative error to leading order, can be expressed superoperator form and use this derive control pulses are robust any class systematic unknown errors. The proposed optimal protocol is equivalent searching for sequence unitaries mimics first-order moments Haar distribution, i.e., it constitutes 1-design. highlight power...

We study a device formed by Bose-Einstein condensate (BEC) coupled to the field of cavity with moving end mirror and find working point such that mirror-light entanglement is reproduced BEC-light quantum correlations. This provides an experimentally viable tool for inferring only limited set assumptions. prove existence tripartite in hybrid device, persisting up temperatures few milli-Kelvin, discuss scheme detect it.

The entanglement spectrum describing quantum correlations in many-body systems has been recently recognized as a key tool to characterize different phases, including topological ones. Here we derive its analytically scaling properties the vicinity of some integrable phase transitions and extend our studies also non one dimensional spin models numerically. Our analysis shows that, all studied cases, difference between two largest degenerate Schmidt eigenvalues yields with good accuracy...

Nonequilibrium thermodynamics is relatively common in a range of scientific fields. Scientists show that observations nonequilibrium can yield predictions quantum many-body systems.

By making use of a recently proposed framework for the inference thermodynamic irreversibility in bosonic quantum systems, we experimentally measure and characterize entropy production rates nonequilibrium steady state two different physical systems—a micromechanical resonator Bose-Einstein condensate—each coupled to high finesse cavity hence also subject optical loss. Key features our setups, such as cooling mechanical signatures structural phase transition condensate, are reflected rates....

We investigate heat engines whose working substance is made of two coupled qubits performing a generalised Otto cycle by varying their applied magnetic field or interaction strength during the compression and expansion strokes. During heating cooling strokes, are to local common environments that not necessarily at equilibrium. find instances quantum non equilibrium exhibiting non-trivial connections correlations as witnessed monotonic dependence work produced on discord entanglement.

The precise knowledge of the temperature an ultracold lattice gas simulating a strongly correlated system is question both, fundamental and technological importance. Here, we address such by combining tools from quantum metrology together with study correlations embedded in at finite temperatures. Within this frame examine spin-$1/2$ XY chain, first estimating, means Fisher information, lowest attainable bound on precision. We then estimation sample analysis using non demolishing Faraday...

Abstract At low-temperatures a gas of bosons will undergo phase transition into quantum state matter known as Bose–Einstein condensate (BEC), in which large fraction the particles occupy ground simultaneously. Here we explore performance an endoreversible Otto cycle operating with harmonically confined Bose working medium. We analyze engine operation three regimes, medium BEC phase, and driven across during each cycle. find that unique properties allow for enhanced performance, including...

In this tutorial, we present the definition, interpretation, and properties of some main quasiprobabilities that can describe statistics measurement outcomes evaluated at two or more times. Such incorporate incompatibility observables state measured quantum system. We particularly focus on Kirkwood-Dirac related distributions. also discuss techniques to experimentally access a quasiprobability distribution, ranging from weak two-point scheme, Ramsey-like interferometric scheme procedures...

Nonequilibrium effects may have a profound impact on the performance of thermal devices performing thermodynamic tasks such as refrigeration or heat pumping. The possibility enhancing operations by means quantum coherence is particular interest but requires an adequate characterization and work at level. In this work, we demonstrate that presence even small amounts in reservoirs powering three-terminal machine, enables appearance combined, hybrid modes operation, where either different...

Perfect state transfer is possible in modulated spin chains [Phys. Rev. Lett. 92, 187902 (2004)], imperfections, however, are likely to corrupt the transfer. We study robustness of this quantum communication protocol presence disorder both exchange couplings between spins and local magnetic field. The degradation fidelity can be suitably expressed, as a function level imperfection length chain, scaling form. In addition time signal becomes fractal. further characterize by analyzing spectral...