Spin-Singlet–Spin-Triplet Transitions in Quantum Dots
ABSTRACT We calculate the rate of the spin-singlet–spin-triplet (ST) relaxation in the two-electron droplet in a magnetic field. Far from the ST crossing point the rate turns out to be rather significant. In connection with the source-drain transport experiments, we consider this result is an explanation of the observed disappearance of the singlet (upper) level at magnetic fields, which are stronger than the ST crossing value.
- SourceAvailable from: ntt.co.jp[Show abstract] [Hide abstract]
ABSTRACT: We describe time-dependent single-electron transport through quantum dots in the Coulomb blockade regime. Coherent dynamics of a single charge qubit in a double quantum dot is discussed with full one-qubit manipulation. Strength of decoherence is controlled with the applied voltage, but uncontrolled decoherence arises from electron–phonon coupling and background fluctuations. Then energy-relaxation dynamics is discussed for orbital and spin degree of freedom in a quantum dot. The electron–phonon interaction and spin–orbit coupling can be investigated as the dissipation problem. Finally, charge detection measurement is presented for statistical analysis of single-electron tunnelling transitions and for a sensitive qubit read-out device.Reports on Progress in Physics 02/2006; 69(3):759. · 13.23 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Both classical and quantum computations operate with the registers of bits. At nanometer scale the quantum fluctuations at the position of a given bit, say, a quantum dot, not only lead to the decoherence of quantum state of this bit, but also affect the quantum states of the neighboring bits, and therefore affect the state of the whole register. That is why the requirement of reliable separate access to each bit poses the limit on miniaturization, i.e, constrains the memory capacity and the speed of computation. In the present paper we suggest an algorithmic way to tackle the problem of constructing reliable and compact registers of quantum bits. We suggest to access the states of quantum register hierarchically, descending from the state of the whole register to the states of its parts. Our method is similar to quantum wavelet transform, and can be applied to information compression, quantum memory, quantum computations.International Journal of Quantum Information 05/2011; · 0.92 Impact Factor