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Electrical control of spin relaxation in a quantum dot
S Amasha1, K Maclean, Iuliana P Radu
1Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. samasha@mit.edu
Physical Review Letters
|March 21, 2008
Summary
We electrically controlled electron spin relaxation times in quantum dots by manipulating orbital states. Spin-orbit interaction and phonon coupling were identified as key relaxation mechanisms, with spin relaxation times exceeding 1 second at 1 T.
Area of Science:
- Quantum computing
- Condensed matter physics
- Spin electronics
Background:
- Single-electron quantum dots are crucial for quantum computing.
- Understanding and controlling electron spin dynamics is essential for qubit stability.
- Spin relaxation time (T1) limits qubit coherence times.
Purpose of the Study:
- To demonstrate electrical control over the spin relaxation time (T1) of a single electron.
- To investigate the role of spin-orbit interaction in spin relaxation.
- To identify dominant relaxation mechanisms in lateral quantum dots.
Main Methods:
- Electrical manipulation of orbital states in a lateral quantum dot using gate voltages.
- Measurement of spin relaxation rate (W = 1/T1) as a function of gate voltage and magnetic field.
- Extraction of spin-orbit length from experimental data.
Main Results:
- Electrical control of spin relaxation rate (W) by over an order of magnitude was achieved.
- The dependence of W on orbital confinement matched theoretical predictions.
- Spin-orbit mediated coupling to phonons was identified as the dominant relaxation mechanism down to 1 Tesla.
- Spin relaxation times (T1) exceeding 1 second were measured at 1 Tesla.
Conclusions:
- Electrical gating provides an effective method for controlling spin relaxation in quantum dots.
- Spin-orbit interaction is a key factor in spin relaxation, influenced by orbital confinement.
- Phonon-mediated relaxation is dominant at low magnetic fields, enabling long spin coherence times.
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