Programme and Abstracts

Session 1

Principles and limits of dissipative state preparation

Abstracts

Speaker: Andrew Pocklington

Title: Accelerating Dissipative State Preparation with Adaptive Open Quantum Dynamics

Abstract: Open quantum systems that are both spatially and temporally local exhibit strict trade-offs between the amount of time it takes to prepare steady state entanglement and how much entanglement can be prepared. In this talk, we will introduce this trade-off and then show how minimally breaking these assumptions (utilizing a single classical bit of memory) can result in drastic speedups. This adaptive scheme is inspired by an analogy to fermionic dynamics, whose intrinsic non-locality allows them circumvent bounds placed on spin systems.

Speaker: Carlos Benavides-Riveros

Title: Augmented Imaginary-Time Evolution: From Asymptotic to Finite-Time Quantum Optimization

Abstract: Imaginary-time evolution (ITE) underpins a broad family of quantum algorithms for quantum simulation, optimization, and ground-state preparation. Yet all existing ITE methods are fundamentally limited by asymptotic convergence, with the energy error decaying only exponentially in imaginary time. In this talk, I will introduce augmented imaginary-time evolution (AITE), a generalized framework that extends conventional ITE by replacing the standard energy-gradient flow with a geometrically informed optimization strategy that exploits the higher-order structure of the instantaneous energy distribution. The resulting flow fundamentally changes the optimization dynamics: AITE strictly outperforms standard ITE throughout the evolution and exhibits two distinct convergence regimes, consisting of an initial superlinear acceleration followed by an extinction regime in which the energy error vanishes exactly at a finite imaginary

time. Standard ITE is recovered as a limiting case of AITE, establishing a unified framework for imaginary-time optimization. Because imaginary-time evolution underlies a wide range of methods in quantum simulation, variational optimization, quantum machine learning, and computational many-body physics, the proposed framework has broad implications across these areas.

Speaker: Parvinder Solanki

Title: Universal relaxation speedup in nonequilibrium quantum many-body systems through transient resetting

Abstract: Speeding up the relaxation dynamics of many-body quantum systems is important in a variety of contexts, including quantum computation and state preparation. We demonstrate that such acceleration can be universally achieved via transient stochastic resetting. This means that during an initial time interval of finite duration, the dynamics is interrupted by resets that take the system to a designated state at randomly selected times. We illustrate this idea for few-body open systems and also for a challenging many-body case, where a first-order phase transition leads to a divergence of relaxation time. In all scenarios, a significant and sometimes even exponential acceleration in reaching the stationary state is observed, similar to the so-called Mpemba effect. The universal nature of this speedup lies in the fact that the design of the resetting protocol only requires knowledge of a few macroscopic properties of the target state, such as the order parameter of the phase transition, while it does not necessitate any fine-tuned manipulation of the initial state.

Speaker: Jerome Lloyd

Title: Quantum thermal state preparation for near-term quantum processors

Abstract: Preparation of thermal and ground states of many-body quantum systems is a central challenge for near-term quantum processors, needed e.g. as the starting point for many quantum physics experiments or for quantum chemistry applications. I will talk about our recent work on efficient state preparation using engineered system-bath physics. After briefly reviewing results from the Google experiment [Science 383 6689 2024], I will explain how time-dependent system-bath couplings can be used to enforce "detailed balance" and controllably prepare thermal and ground states with high accuracies. The resulting algorithm is particularly suitable for near-term devices, requiring only ancilla reset, local couplings, and Hamiltonian evolution. 

Speaker: Nicolò Beato

Title: Harnessing multi- and metastability in open quantum systems 

Abstract: Long-lived transients in open quantum systems, arising from multistability or metastability, often determine the observable properties in quantum experiments. In this talk, I will show how a single unitary operation, applied before the dissipative evolution, can select which long-lived phase the system realizes and how it approaches it. Building on a recent technique that tunes relaxation timescales by cancelling selected modes of the Liouvillian dynamics, I will use a partition of the Hilbert space based on committor operators to identify basins of attraction and assign each fast relaxation mode to each of them. This geometric decomposition reproduces the familiar picture in the semiclassical limit, but it extends to systems far from, or entirely lacking, such a limit. I will illustrate the method in three spin models, where the choice of basin fixes the magnetization throughout the metastable plateau or switches the steady-state spin current, and discuss prospects for implementation in current quantum simulators.

Speaker: Sebastian Paeckel

Title: Unlocking Low-Energy Many-Body Spectra with Dynamic Krylov Frames

Abstract: The recent years have seen enormous experimental progress in designing and controlling strongly correlated quantum materials. At the same time, this progress poses new challenges for theoretical and numerical methods. A particularly pressing problem is the efficient computation of low-energy spectra in strongly correlated systems beyond one spatial dimension.

In this talk, I will introduce dynamic non-unitary Krylov frames as a new framework for addressing this challenge. Building on the recent success of complex-time methods, dynamic non-unitary Krylov frames provide a unifying theoretical framework and a foundation for developing highly efficient numerical approaches to many-body spectral problems.

As an example, I will consider two-hole bound states in the two-dimensional t-J model. I will show how exploiting the structure of dynamic non-unitary Krylov frames enables energy resolutions at low energies that are inaccessible with conventional approaches. These results demonstrate how the framework can bridge the gap between effective microscopic theories and experimentally relevant energy scales, opening new perspectives for understanding pairing mechanisms in unconventional superconductors.