Single-spin measurement using spin–orbital entanglement

Abstract

Single spin measurement represents a major challenge for spin-based quantum computation. In this article we propose a new method for measuring the spin of a single electron confined in a quantum dot (QD). Our strategy is based on entangling (using unitary gates) the spin and orbital degrees of freedom. An orbital qubit, defined by a second, empty QD, is used as an ancilla and is prepared in a known initial state. Measuring the orbital qubit will reveal the state of the (unknown) initial spin qubit, hence reducing the problem to the easier task of single charge measurement. Since spin-charge conversion is done with unit probability, single-shot measurement of an electronic spin can be, in principle, achieved. We evaluate the robustness of our method against various sources of error and discuss possible implementations.

Cyclic permutations for qudits in d dimensions

“…To arrive at this setup, we use quantum information methods and quantum network analysis. This approach has been employed previously to design a universal quantum sorter 19 and spin measuring devices 20,21 .…”

Spin-orbit effects in single-electron states in coupled quantum dots

“…A single charge measurement on one dot collapses the wave function to the corresponding spin state, realizing a spin to charge conversion. There exist several alternative schemes, [40][41][42][43] some of them being pursued experimentally. 24,25,44 We construct an effective, four state ͑two spin and two sites͒ tunneling Hamiltonian for the single-electron double dot system, which takes into effect the above results.…”

Scheme for Implementing Controlled Quantum Teleportation in QDS-Cavity System

“…By using the conditional Faraday rotation (Leuenberger, Flatté, and Awschalom 2005;Leuenberger 2006) of the polarization of single photons, single photons detection (Leuenberger, Flatté, and Awschalom 2005;Leuenberger 2006;Ionicioiu and A. E. Popescu 2005;Rugar et al 2004;Santori et al 2002) and electron spin orientation measurement, the CQT of tripartite GHZ-Like state encoded in the electron spins in QDs can be realized in terms of theory perfectly and we find that the success probability of CQT can reach 1 by choosing the appropriate Faraday rotation angle for the switchable micro-cavities. The CQT scheme for implementing the teleportation of tripartite or multipartite GHZ-Like state discussed here can be used for QT but the new system here with three QDs in the controlling microcavity is much more complicated than the previous system with a single quantum dot embedded inside the controlling microcavity (Hu, Jin, and Wang 2010).…”