We demonstrate that dissipative state preparation protocols in many-body systems can be substantially accelerated via the quantum Mpemba effect. Our approach exploits weak symmetries to analytically identify a class of simple, experimentally realizable states that converge exponentially faster to the steady state than typical random initializations. In particular, we study the preparation of a lattice Bose-Einstein condensate (BEC), where the depletion can be controlled via the dissipation strength. We also show how to tune the momentum of the created high-fidelity BEC by combining superfluid immersion with lattice shaking. Our theoretical predictions are confirmed by numerical simulations of the dissipative dynamics. This protocol paves the way to unlock the enormous potential of the dissipative preparation of highly entangled states in analog quantum simulators.
We demonstrate that dissipative state preparation protocols in many-body systems can be substantially accelerated via the quantum Mpemba effect. Our approach exploits weak symmetries to analytically identify a class of simple, experimentally realizable states that converge exponentially faster to the steady state than typical random initializations. In particular, we study the preparation of a lattice Bose-Einstein condensate (BEC), where the depletion can be controlled via the dissipation strength. We also show how to tune the momentum of the created high-fidelity BEC by combining superfluid immersion with lattice shaking. Our theoretical predictions are confirmed by numerical simulations of the dissipative dynamics. This protocol paves the way to unlock the enormous potential of the dissipative preparation of highly entangled states in analog quantum simulators.
Open quantum systems, where quantum dynamics is influenced by (non-)Markovian environments, have attracted increasing attention due to their rich physical properties. Understanding phenomena such as non-equilibrium phases, anomalous thermalization, and dissipative state preparation requires the knowledge of the low-lying eigenvalues and eigenstates of the Lindbladian. In this thesis, we introduce a framework that systematically computes not only steady states but also low-lying excited states in large, dissipative, interacting quantum many-body systems. The framework is based on tensor-network methods and utilizes recent advances in complex-time Krylov spaces. Extending these ideas to the challenging non-Hermitian eigenvalue problem ubiquitous in open quantum systems enables simulations at unprecedented Hilbert space dimensions. We employ the framework to analyze a dissipative state preparation protocol for Bose-Einstein condensates (BECs) on optical lattices. Analytical and numerical studies allow us to characterize the steady state and perform a finite-size scaling of the dissipative gap, uncovering strong evidence for non-linear hydrodynamics described by the Kardar-Parisi-Zhang universality class. Furthermore, we show analytically that the dissipative state preparation can be substantially accelerated via the quantum Mpemba effect. Our approach exploits weak symmetries to analytically identify a class of simple, experimentally realizable states that converge exponentially faster to the steady state than typical random initializations. Overall, this work establishes a versatile framework for the spectral analysis of generic open quantum many-body systems, enabling the analysis of complex collective phenomena and additionally paving the way toward faster dissipative preparation of highly entangled states in analog quantum simulators.
The Mpemba effect, where a state farther from equilibrium relaxes faster than one closer to it, is a striking phenomenon in both classical and quantum systems. In open quantum systems, however, the quantum Mpemba effect (QME) typically occurs only for specifically chosen initial states, which limits its universality. Here we present a general and experimentally feasible strategy to realize both QME and anti-QME. By applying a temporary bond-dissipation quench, we selectively suppresses or enhances slow relaxation modes, thereby reshaping relaxation pathways independently of both the system and the initial state. We demonstrate this mechanism in systems with dephasing and boundary dissipation, and outline feasible cold-atom implementations. Our results establish controllable dissipation as a versatile tool for quantum control, accelerated relaxation, and efficient nonequilibrium protocols.
The Mpemba effect, where a hotter system cools faster than a colder one under otherwise identical conditions, has been extensively studied in classical systems. In this work, we present the quantum analogue of the Mpemba effect using a dissipative qubit, which is referred to as the canonical quantum Mpemba effect. We demonstrate that, under the identical conditions, the relaxation dynamics of a qubit initialized in a thermal state with a higher temperature can be exponentially faster than those of a colder thermal state. Strikingly, this acceleration is determined solely by the initial temperature of the system, independent of other parameters. The relaxation is confirmed to be a genuine cooling process via the effective steady state temperature, mirroring its classical counterpart. Last, we propose a practical classical quantum hybrid algorithmic quantum circuit to realize this effect using superconducting qubits experimentally.
Generating entanglement rapidly and reliably is essential for quantum information processing, communication, and metrology. Dissipative preparation is attractive because engineered reservoirs robustly drive a system toward an entangled target, yet relaxation can carry a substantial time cost. Here we formulate the entanglement Mpemba effect, whereby an initially less entangled state overtakes a more entangled state under the same open-system dynamics. This effect turns initial-state engineering into a route for faster preparation without altering the dissipative protocol. We derive a general criterion for the reversal from the relaxation spectrum, applicable even when entanglement evolves nonmonotonically. A reversal of deterministic local operations and classical communication (LOCC)-reachability preorder provides a measure-independent certificate of reversed entanglement order. Exactly solvable models show that initial-state selection can substantially shorten the time required to reach high entanglement. We further propose an experimentally relevant trapped-ion protocol that can realize the entanglement Mpemba effect.
We investigate the quantum Mpemba effect in the relaxation of open quantum systems whose effective dynamics is described by Davies maps. We introduce a class of unitary transformations constructed from permutation matrices that, when applied to an initial state, (i) suppress the slowest decaying modes of the nonunitary dynamics and (ii) maximize the state's distinguishability from the steady state. The first condition ensures exponentially faster convergence to equilibrium, while the second implies that a quantum system initially further from equilibrium can approach it more rapidly than one that starts closer. This protocol thus realizes a genuine Mpemba effect, and its simulation requires low computational effort. We prove that, for any initial state, there exists a permutation matrix that maximizes its distance from equilibrium with respect to a chosen information-theoretic distinguishability measure. We illustrate our findings for a two-level system, as well as for the nonunitary dynamics of the transverse-field Ising chain and the XXZ chain, each weakly coupled to a bosonic thermal bath. In these cases, the quantum Mpemba effect is demonstrated using the Hilbert-Schmidt distance, quantum relative entropy, and trace distance. Overall, our results provide a versatile framework for engineering a genuine quantum Mpemba effect in Markovian open quantum systems.
The quantum Mpemba effect (QME) is a phenomenon observed in many-body systems where initial systems configurations farther from equilibrium can be observed to equilibrate faster than configurations that are closer to it. By considering noise induced error in the initial system state preparation, we analyse the robustness of various models exhibiting the QME. We demonstrate that exponentially accelerated thermalisation in open system dynamics modelled by a Gorini-Kossakowski-Sudarshan-Lindblad master equation is highly sensitive to noise induced deviations in the initial state, making this approach to accelerated thermalisation difficult to achieve. In contrast, we demonstrate that accelerated restoration of symmetry in U(1) symmetric random unitary circuits via increased initial symmetry breaking is robust in the presence of state preparation error. When large errors are present in the state preparation, we show that this can in fact induce a higher rate of symmetry restoration and a stronger QME.