Title: Quantum Communication for Spin Qubits

Xuedong Hu, Department of Physics, University at Buffalo

Abstract: Recent experimental and theoretical research on spin qubits in quantum dots

have clearly demonstrated that spins have long coherence time and can be reliably

controlled.  Electron spin two-qubit gates can be performed using the strong exchange

interaction, which however is short-ranged. How to achieve long-range quantum

communication for spin qubits thus remains a significant open problem in the scale-up

of spin qubit architectures.  In this talk I will give an overview of the various

approaches to achieve spin information transfer, such as those based on spin-photon

coupling, or based on a spin bus made from a spin chain.  I will then focus on a

particular approach that involves the transportation of the electrons themselves,

which is attractive because of its conceptual simplicity and its similarity to the

conventional charge-coupled devices. Indeed, recently several experimental groups have

shown how an electron can be transported over a distance of several microns between two

quantum dots by a surface acoustic wave (SAW) in GaAs.  I will discuss our recent work

on the physics of electron spin decoherence when the quantum dot is in motion.

Specifically, we find that the motion induced spin decoherence is a pure longitudinal

relaxation channel.  Our results not only show how severe a problem this decoherence

could be, but also clearly indicate how to reduce the decoherence effects of electron

motion.

We thank support by US ARO, DARPA QuEST, and NSF PIF.

Dec 10, 2012 at 2:30 pm
RAC1 2009
https://services.iqc.uwaterloo.ca/visitors/talks/talk/283/