CM Seminar - Lincoln Carr, Colorado School of Mines

Lincoln Carr

Event Date

Location
Physics 185

Speaker: Lincoln Carr, Colorado School of Mines

Title: Many-body quantum decoherence and reservoir engineering

Abstract: The most common spec given for a quantum computer besides the number of qubits is the T1 and T2 decoherence times, both of which are based on a single qubit interacting with the environment. The quantum volume, one measure for the capability of quantum computer, combines the number of qubits, T1 and T2 decoherence times, and the physical connectivity between qubits. However, a different kind of connectivity arises in the quantum state itself, entanglement, which can make the quantum volume a poor predictor of quantum computing performance. Entanglement is delocalized in many quantum calculations, for example when simulating condensed matter systems near critical points. It is the entire quantum wavefunction which interacts with the environment, leading to the concept of many-body quantum decoherence. Using the quantum Ising model as a working example, I will show how many-body quantum decoherence combined with reservoir engineering leads to many surprises, such as more qubits being better, not worse, and the decoherence time depending on the proximity to the quantum critical point. In quantum dynamics I will demonstrate practical effects of structured, distributed entanglement on decoherence times in quantum cellular automata implemented on Google’s quantum computer. Finally, I will suggest an ideal system for exploring many-body quantum decoherence and reservoir engineering in ultracold molecules with highly controlled internal degrees of freedom.