Abstract
The main objective of quantum simulation is an in-depth understanding of many-body physics, which is important for fundamental issues (quantum phase transitions, transport, …) and for the development of innovative materials. Analytic approaches to many-body systems are limited, and the huge size of their Hilbert space makes numerical simulations on classical computers intractable. A quantum simulator avoids these limitations by transcribing the system of interest into another, with the same dynamics but with interaction parameters under control and with experimental access to all relevant observables. Quantum simulation of spin systems is being explored with trapped ions, neutral atoms, and superconducting devices. We propose here a new paradigm for quantum simulation of spin- arrays, providing unprecedented flexibility and allowing one to explore domains beyond the reach of other platforms. It is based on laser-trapped circular Rydberg atoms. Their long intrinsic lifetimes, combined with the inhibition of their microwave spontaneous emission and their low sensitivity to collisions and photoionization, make trapping lifetimes in the minute range realistic with state-of-the-art techniques. Ultracold defect-free circular atom chains can be prepared by a variant of the evaporative cooling method. This method also leads to the detection of arbitrary spin observables with single-site resolution. The proposed simulator realizes an spin- Hamiltonian with nearest-neighbor couplings ranging from a few to tens of kilohertz. All the model parameters can be dynamically tuned at will, making a large range of simulations accessible. The system evolution can be followed over times in the range of seconds, long enough to be relevant for ground-state adiabatic preparation and for the study of thermalization, disorder, or Floquet time crystals. The proposed platform already presents unrivaled features for quantum simulation of regular spin chains. We discuss extensions towards more general quantum simulations of interacting spin systems with full control on individual interactions.
- Received 14 July 2017
- Revised 16 October 2017
DOI:https://doi.org/10.1103/PhysRevX.8.011032
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Materials such as superconductors or topological insulators derive their properties from the interactions of their numerous quantum systems. Numerical simulations of such materials are daunting because the computation time grows exponentially with the number of interacting components. An alternative approach is to use a quantum simulator, an ensemble of quantum particles that can be manipulated to solve complex problems. The simulator has the same dynamics as the system under investigation; however, each of its particles can be prepared in a chosen state, the interactions can be controlled, and the particles can be individually measured. Quantum simulators are being developed with superconducting circuits, ions, cold atoms, and Rydberg atoms (atoms with one or more highly excited electrons). We propose an alternative platform based on laser-trapped circular Rydberg atoms, which has the potential of performing simulations at unprecedented time scales.
Circular states are quantum counterparts of Bohr’s circular atomic orbit. They are impervious to photoionization and can be laser trapped. Their main decay, microwave spontaneous emission, is inhibited in a plane-parallel capacitor, leading to lifetimes in the minute range. We propose an innovative deterministic preparation and detection of defect-free chains. The atoms emulate a general () spin Hamiltonian, whose parameters are all under control. The dynamics of a few tens of interacting atoms could be followed over characteristic elementary interaction times.
Our approach provides a way to study systems with slow dynamics such as spin glasses—exotic materials in which electron spins continually fluctuate and never align. The manipulations of laser-trapped circular states can also lead to interesting developments in quantum metrology or cavity quantum electrodynamics experiments.
