RSS icon
Twitter icon
Facebook icon
Vimeo icon
YouTube icon

A coherent beam splitter for electronic spin states

April 5, 2010 - 12:30pm
Speaker: 
Jason Petta
Institution: 
Princeton

Energy level crossings, where two quantum states cross in energy as a function of an external parameter, are ubiquitous in quantum mechanics. We demonstrate coherent control of electronic spin states in a double quantum dot by sweeping an initially prepared spin singlet state through a singlet-triplet anti-crossing in the energy level spectrum.1 The anti-crossing serves as a beam splitter for the incoming spin singlet state. Consecutive crossings through the beam splitter, when performed within the spin dephasing time, result in controllable coherent quantum oscillations between the singlet state and triplet state. The observed quantum interference patterns are in good agreement with a theoretical model of consecutive Landau-Zener tunneling events.2 This all-electrical method for quantum control relies on electron-nuclear spin coupling and drives single electron spin rotations on nanosecond timescales without electron spin resonance fields, which are difficult to localize on the nanometer scale. 

1. J. R. Petta, H. Lu, A. C. Gossard, Science (in press).
2. H. Ribeiro, J. R. Petta, G. Burkard (unpublished).

1201 Physics Building
College Park, MD 20742

Subscribe to A Quantum Bit 

Quantum physics began with revolutionary discoveries in the early twentieth century and continues to be central in today’s physics research. Learn about quantum physics, bit by bit. From definitions to the latest research, this is your portal. Subscribe to receive regular emails from the quantum world. Previous Issues...

Sign Up Now

Sign up to receive A Quantum Bit in your email!

 Have an idea for A Quantum Bit? Submit your suggestions to jqi-comm@umd.edu