Weak-measurement theory of quantum-dot spin qubits
Abstract
The theory of weak quantum measurements is developed for quantum-dot spin qubits. Building on recent experiments, we propose a control cycle to prepare, manipulate, weakly measure, and perform quantum state tomography. This is accomplished using a combination of the physics of electron spin resonance, spin blockade, and Coulomb blockade, resulting in a charge transport process. We investigate the influence of the surrounding nuclear spin environment, and find a regime where this environment significantly simplifies the dynamics of the weak-measurement process, making this theoretical proposal realistic with existing experimental technology. We further consider spin-echo refocusing to combat dephasing, as well as discuss a realization of “quantum undemolition,” whereby the effects of quantum state disturbance are undone.
- Publication:
-
Physical Review B
- Pub Date:
- October 2007
- DOI:
- 10.1103/PhysRevB.76.155324
- arXiv:
- arXiv:0706.0180
- Bibcode:
- 2007PhRvB..76o5324J
- Keywords:
-
- 03.65.Ta;
- 03.67.Lx;
- 73.63.Kv;
- 76.30.-v;
- Foundations of quantum mechanics;
- measurement theory;
- Quantum computation;
- Quantum dots;
- Electron paramagnetic resonance and relaxation;
- Condensed Matter - Mesoscopic Systems and Quantum Hall Effect;
- Quantum Physics
- E-Print:
- 8 pages, 2 figures