100 citations · 815 across the 28 of their papers we have counts for
28 papers · 1 filter
Efficient Quantum Monte Carlo through Cluster Expansions
Jorge Sánchez-Segovia, Álvaro M. Alhambra
The sign problem remains a major obstacle to extending the success of Monte Carlo methods to generic quantum many-body systems. A powerful alternative relies on cluster expansions,…
Thermalization in open many-body systems and KMS detailed balance
Matteo Scandi, Álvaro M. Alhambra
Starting from a microscopic description of weak system-bath interactions, we derive from first principles a quantum master equation that does not rely on the well-known rotating wa…
Optimal quantum algorithm for Gibbs state preparation
Cambyse Rouzé, Daniel Stilck França, Álvaro M. Alhambra
It is of great interest to understand the thermalization of open quantum many-body systems, and how quantum computers are able to efficiently simulate that process. A recently intr…
The product structure of MPS-under-permutations
Marta Florido-Llinàs, Álvaro M. Alhambra, Rahul Trivedi +3
Tensor network methods have proved to be highly effective in addressing a wide variety of physical scenarios, including those lacking an intrinsic one-dimensional geometry. In such…
Regular language quantum states
Marta Florido-Llinàs, Álvaro M. Alhambra, David Pérez-García +1
We introduce regular language states, a family of quantum many-body states. They are built from a special class of formal languages, called regular, which has been thoroughly studi…
Rapid thermalization of dissipative many-body dynamics of commuting Hamiltonians
Jan Kochanowski, Alvaro M. Alhambra, Angela Capel +1
Quantum systems typically reach thermal equilibrium rather quickly when coupled to a thermal environment. The usual way of bounding the speed of this process is by estimating the s…
Efficient thermalization and universal quantum computing with quantum Gibbs samplers
Cambyse Rouzé, Daniel Stilck França, Álvaro M. Alhambra
The preparation of thermal states of matter is a crucial task in quantum simulation. In this work, we prove that a recently introduced, efficiently implementable dissipative evolut…
Conditional Independence of 1D Gibbs States with Applications to Efficient Learning
Álvaro M. Alhambra, Ángela Capel, Paul Gondolf +2
We show that spin chains in thermal equilibrium have a correlation structure in which individual regions are strongly correlated at most with their near vicinity. We quantify this…
Matrix product state approximations to quantum states of low energy variance
Kshiti Sneh Rai, J. Ignacio Cirac, Álvaro M. Alhambra
We show how to efficiently simulate pure quantum states in one dimensional systems that have both finite energy density and vanishingly small energy fluctuations. We do so by study…
Classical simulation of short-time quantum dynamics
Dominik S. Wild, Álvaro M. Alhambra
Recent progress in the development of quantum technologies has enabled the direct investigation of dynamics of increasingly complex quantum many-body systems. This motivates the st…
Quantum many-body systems in thermal equilibrium
Álvaro M. Alhambra
The thermal or equilibrium ensemble is one of the most ubiquitous states of matter. For models comprised of many locally interacting quantum particles, it describes a wide range of…
Eigenstate entanglement in integrable collective spin models
Meenu Kumari, Álvaro M. Alhambra
The average entanglement entropy (EE) of the energy eigenstates in non-vanishing partitions has been recently proposed as a diagnostic of integrability in quantum many-body systems…
Locally accurate tensor networks for thermal states and time evolution
Álvaro M. Alhambra, J. Ignacio Cirac
Tensor network methods are routinely used in approximating various equilibrium and non-equilibrium scenarios, with the algorithms requiring a small bond dimension at low enough tim…
Computable Rényi mutual information: Area laws and correlations
Samuel O. Scalet, Álvaro M. Alhambra, Georgios Styliaris +1
The mutual information is a measure of classical and quantum correlations of great interest in quantum information. It is also relevant in quantum many-body physics, by virtue of s…
Optimal Quantum Thermometry with Coarse-grained Measurements
Karen V. Hovhannisyan, Mathias R. Jørgensen, Gabriel T. Landi +3
Precise thermometry for quantum systems is important to the development of new technology, and understanding the ultimate limits to precision presents a fundamental challenge. It i…
Improved thermal area law and quasi-linear time algorithm for quantum Gibbs states
Tomotaka Kuwahara, Álvaro M. Alhambra, Anurag Anshu
One of the most fundamental problems in quantum many-body physics is the characterization of correlations among thermal states. Of particular relevance is the thermal area law, whi…
Mixing and localisation in random time-periodic quantum circuits of Clifford unitaries
Tom Farshi, Daniele Toniolo, Carlos E. González-Guillén +2
How much does local and time-periodic dynamics resemble a random unitary? In the present work we address this question by using the Clifford formalism from quantum computation. We…
Revivals imply quantum many-body scars
Álvaro M. Alhambra, Anurag Anshu, Henrik Wilming
We derive general results relating revivals in the dynamics of quantum many-body systems to the entanglement properties of energy eigenstates. For a D-dimensional lattice system of…
Time evolution of correlation functions in quantum many-body systems
Álvaro M. Alhambra, Jonathon Riddell, Luis Pedro García-Pintos
We give rigorous analytical results on the temporal behavior of two-point correlation functions --also known as dynamical response functions or Green's functions-- in closed many-b…
Continuous groups of transversal gates for quantum error correcting codes from finite clock reference frames
Mischa P. Woods, Álvaro M. Alhambra
Following the introduction of the task of reference frame error correction, we show how, by using reference frame alignment with clocks, one can add a continuous Abelian group of t…
Work distributions on quantum fields
Alvaro Ortega, Emma McKay, Álvaro M. Alhambra +1
We study the work cost of processes in quantum fields without the need of projective measurements, which are always ill defined in quantum field theory. Inspired by interferometry…
Fundamental limitations to local energy extraction in quantum systems
Álvaro M. Alhambra, Georgios Styliaris, Nayeli A. Rodriguez-Briones +2
We examine when it is possible to locally extract energy from a bipartite quantum system in the presence of strong coupling and entanglement, a task which is expected to be restric…
Mixing of quantum states under Markovian dissipation and coherent control
Georgios Styliaris, Álvaro M. Alhambra, Paolo Zanardi
Given any two quantum states and in Hilbert spaces of equal dimension satisfying the majorization condition , it is always possible to transform by a…
Heat-Bath Algorithmic Cooling with optimal thermalization strategies
Álvaro M. Alhambra, Matteo Lostaglio, Christopher Perry
Heat-Bath Algorithmic Cooling is a set of techniques for producing highly pure quantum systems by utilizing a surrounding heat-bath and unitary interactions. These techniques origi…