We work on the investigation of quantum annealing, a framework for computation that relies on the preparation of ground or low energy states of complex Hamiltonians. This framework has a wide variety of potential applications, ranging from optimization problems to machine learning.This work is part of the Quantum Enhanced Optimization program and is done in collaboration with academic, industry, and government groups. The SQD group works on several topics related to quantum annealing, some of which are discussed below.
Many-body interactions are relevant in various areas in quantum information. In quantum annealing many-body interactions can be used for implementation of error correction and for more efficient embedding of optimization problems. We proposed and analyzed a new superconducting circuit that implements a three body interaction between flux qubits. This coupler circuit has a tunable interaction reaching coupling strengths of the order of 1 GHz, has negligible spurious two body terms, is robust against parameter variations nd noise, and is implemented using a simple circuit.
The efficiency of quantum annealing is impacted by excitation processes out of the ground state of a quantum annealer, due to Landau-Zener tunneling and environmental effects. We investigate adaptive annealing : the state of the annealer is monitored during evolution and suitable feedback is used to reduced unwanted transitions to excited states.