Experimental Realization of Classical ${\mathbb{Z}}_2$ Spin Liquids in a Programmable Quantum Device

Abstract

We build and probe a ${\mathbb{Z}}_2$ spin liquid in a programmable quantum device, the D-Wave DW-2000Q. Specifically, we observe the classical 8-vertex and 6-vertex (spin ice) states and transitions between them. To realize this state of matter, we design a Hamiltonian with combinatorial gauge symmetry using only pairwise-qubit interactions and a transverse field, i.e., interactions which are accessible in this quantum device. The combinatorial gauge symmetry remains exact along the full quantum annealing path, landing the system onto the classical 8-vertex model at the endpoint of the path. The output configurations from the device allows us to directly observe the loop structure of the classical model. Moreover, we deform the Hamiltonian so as to vary the weights of the 8 vertices and show that we can selectively attain the classical 6-vertex (ice) model, or drive the system into a ferromagnetic state. We present studies of the classical phase diagram of the system as function of the 8-vertex deformations and effective temperature, which we control by varying the relative strengths of the programmable couplings, and we show that the experimental results are consistent with theoretical analysis. Finally, we identify additional capabilities that, if added to these devices, would allow us to realize ${\mathbb{Z}}_2$ quantum spin liquids on which to build topological qubits.

6 pages, 5 figures

References in corpus (3)

• Topological Order and Conformal Quantum Critical Points
• Experimental identification of quantum spin liquids
• Topological phases and topological entropy of two-dimensional systems with finite correlation length

Cited by in corpus (11)

• Probing Topological Spin Liquids on a Programmable Quantum Simulator
• Quantum critical dynamics in a 5000-qubit programmable spin glass
• Comparing Three Generations of D-Wave Quantum Annealers for Minor Embedded Combinatorial Optimization Problems
• Quantum circuits for the preparation of spin eigenfunctions on quantum computers
• Breakdown of the weak coupling limit in quantum annealing
• Simulating the Transverse Field Ising Model on the Kagome Lattice using a Programmable Quantum Annealer
• Preparing ground states of the XXZ model using the quantum annealing with inductively coupled superconducting flux qubits
• Probing fractional statistics in quantum simulators of spin liquid Hamiltonians
• Anderson localization of emergent quasiparticles: Spinon and vison interplay at finite temperature in a ${\mathbb{Z}}_2$ gauge theory in three dimensions
• Perfectly hidden order and Z2 confinement transition in a fully packed monopole liquid
• Mapping State Transition Susceptibility in Quantum Annealing