Hassan Halataei, Institute for Research in Fundamental Sciences (PQI Seminar)

Pure dephasing effects in superconducting flux qubits and classical simulation of entanglement

Zoom Link: https://pitt.zoom.us/j/92738959286

Abstract: 

Advancements in the technology of quantum bits invoke more precise calculations of decoherence and dissipative effects. Such noise effects are a result of entanglement of qubits with their surrounding environment. It is interesting to see if the entanglement can be simulated by classical noises without the need for the environment and to explore possible connections with a simulation of a general-purpose quantum computer with noisy qubits. As the quantum computing era is approaching it is also interesting to ask how we are going to effectively protect our security against quantum computer attacks and what practical applications current quantum machines can have for us.

In this talk, I first revisit the physics of double-well potentials and truncated two-level systems and show that in some systems, such as in triple-junction superconducting flux qubit, classical or quantum environmental noises that are usually recognized to only have dissipative effects and the trivial resultant dephasing, can also cause pure dephasing. I then demonstrate how an arbitrary quantum environmental noise that acts on one qubit can be simulated by classical noises and consequently how entanglement can be modeled by random unitary evolutions. I finally discuss some new interests in post-quantum cryptography, Ising solvers, and practical applications of D-Wave quantum computers.