Abstract
Quantum antiferromagnets with geometrical frustration exhibit rich many-body physics but are hard to simulate by means of classical computers. Although quantum-simulation studies for analyzing such systems are thus desirable, they are still limited to high-temperature regions, where interesting quantum effects are smeared out. Here we propose a feasible protocol to perform analog quantum simulation of frustrated antiferromagnetism with strong quantum fluctuations by using ultracold Bose gases in optical lattices at negative absolute temperatures. Specifically, we show from numerical simulations that the time evolution of a negative-temperature state subjected to a slow sweep of the hopping energy simulates quantum phase transitions of a frustrated Bose–Hubbard model with sign-inverted hoppings. Moreover, we quantitatively predict the phase boundary between the frustrated superfluid and Mott-insulator phases for triangular lattices with hopping anisotropy, which serves as a benchmark for quantum simulation.
Highlights
Quantum antiferromagnets with geometrical frustration exhibit rich many-body physics but are hard to simulate by means of classical computers
A system of Bose gases in a deep optical lattice is described by the Bose–Hubbard model: H^
We proposed an experimental protocol to create a frustrated quantum state at negative absolute temperature by performing a phase imprinting together with sudden inversion of the interatomic interaction and the trap potential
Summary
Quantum antiferromagnets with geometrical frustration exhibit rich many-body physics but are hard to simulate by means of classical computers. We propose a feasible protocol to perform analog quantum simulation of frustrated antiferromagnetism with strong quantum fluctuations by using ultracold Bose gases in optical lattices at negative absolute temperatures. The study on the interplay of the frustration and strong quantum fluctuations has been one of the core challenges of quantum many-body physics, presenting many open problems in connection with nontrivial magnetic states including quantum spin liquids[3] and as a challenge for numerical techniques to handle highly entangled ground states[4,5]. Quantum simulation with the use of ultracold atomic gases in optical lattices[6,7,8] has been discussed as a promising approach to make a critical breakthrough in this research area.
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