Controlling Spin Qubits in Quantum Dots

AbstractWe review progress on the spintronics proposal for quantum computing where the quantum bits (qubits) are implemented with electron spins. We calculate the exchange interaction of coupled quantum dots and present experiments, where the exchange coupling is measured via transport. Then, experiments on single spins on dots are described, where long spin relaxation times, on the order of a millisecond, are observed. We consider spin-orbit interaction as sources of spin decoherence and find theoretically that also long decoherence times are expected. Further, we describe the concept of spin filtering using quantum dots and show data of successful experiments. We also show an implementation of a read out scheme for spin qubits and define how qubits can be measured with high precision. Then, we propose new experiments, where the spin decoherence time and the Rabi oscillations of single electrons can be measured via charge transport through quantum dots. Finally, all these achievements have promising applications both in conventional and quantum information processing. PACS: 03.67.Lx, 03.67.Mn, 73.23.Hk, 85.35.Be

[1]  C. Gould,et al.  Readout of a single electron spin based quantum bit by current detection , 2001 .

[2]  Wei Lu,et al.  Real-time detection of electron tunnelling in a quantum dot , 2003, Nature.

[3]  A. Khaetskii,et al.  Spin-flip transitions between Zeeman sublevels in semiconductor quantum dots , 2000, cond-mat/0003513.

[4]  A C Gossard,et al.  Spin and polarized current from Coulomb blockaded quantum dots. , 2003, Physical review letters.

[5]  Jr.,et al.  Low-Temperature Saturation of the Dephasing Time and Effects of Microwave Radiation on Open Quantum Dots , 1999, cond-mat/9904274.

[6]  Single Spin Dynamics and Decoherence in a Quantum Dot via Charge Transport , 2001, cond-mat/0109470.

[7]  Ritchie,et al.  Measurements of Coulomb blockade with a noninvasive voltage probe. , 1993, Physical review letters.

[8]  R. Fiederling,et al.  Injection and detection of a spin-polarized current in a light-emitting diode , 1999, Nature.

[9]  N. C. van der Vaart,et al.  Changes in the magnetization of a double quantum dot , 1998 .

[10]  D. DiVincenzo,et al.  Coupled quantum dots as quantum gates , 1998, cond-mat/9808026.

[11]  Hyperfine-mediated transitions between a Zeeman split doublet in GaAs quantum dots: The role of the internal field , 2002, cond-mat/0202237.

[12]  G. J. Milburn,et al.  Single Spin Measurement using Single Electron Transistors to Probe Two Electron Systems , 2000 .

[13]  G. A. Prinz,et al.  Spin‐Polarized Transport , 1995 .

[14]  Loss,et al.  Quantum dot as spin filter and spin memory , 2000, Physical review letters.

[15]  S. Tarucha,et al.  Allowed and forbidden transitions in artificial hydrogen and helium atoms , 2002, Nature.

[16]  Waugh,et al.  Single-electron charging in double and triple quantum dots with tunable coupling. , 1995, Physical review letters.

[17]  A. Gossard,et al.  Gigahertz Electron Spin Manipulation Using Voltage-Controlled g-Tensor Modulation , 2003, Science.

[18]  P. Matagne,et al.  Experiments And Simulations On A Few‐Electron Quantum Dot Circuit With Integrated Charge Read‐Out , 2002, cond-mat/0212489.

[19]  D. K. Young,et al.  Electrical spin injection in a ferromagnetic semiconductor heterostructure , 1999, Nature.

[20]  R. Blick,et al.  Formation of a Coherent Mode in a Double Quantum Dot , 1998 .

[21]  L. Sohn,et al.  Mesoscopic electron transport , 1997 .

[22]  C. Marcus,et al.  A Gate-Controlled Bidirectional Spin Filter Using Quantum Coherence , 2003, Science.

[23]  Daniel Loss,et al.  Electron spin evolution induced by interaction with nuclei in a quantum dot , 2003 .

[24]  T. Honda,et al.  Shell Filling and Spin Effects in a Few Electron Quantum Dot. , 1996, Physical review letters.

[25]  L. Levitov,et al.  Dynamical spin-electric coupling in a quantum dot , 2002, cond-mat/0209507.

[26]  A. Gossard,et al.  Electrical control of spin precession in semiconductor quantum wells , 2003 .

[27]  D. DiVincenzo,et al.  The Physical Implementation of Quantum Computation , 2000, quant-ph/0002077.

[28]  H. Cheong,et al.  Coherent manipulation of electronic States in a double quantum dot. , 2003, Physical review letters.

[29]  A. Khaetskii,et al.  Electron spin decoherence in quantum dots due to interaction with nuclei. , 2002, Physical review letters.

[30]  Daniel Loss,et al.  Spintronics and quantum dots for quantum computing and quantum communication , 2000 .

[31]  D D Awschalom,et al.  Ultrafast Manipulation of Electron Spin Coherence , 2001, Science.

[32]  Nitin Samarth,et al.  Room-Temperature Spin Memory in Two-Dimensional Electron Gases , 1997 .

[33]  Stuart A. Wolf,et al.  Spintronics : A Spin-Based Electronics Vision for the Future , 2009 .

[34]  D. Loss,et al.  Detection of single spin decoherence in a quantum dot via charge currents. , 2000, Physical review letters.

[35]  Su,et al.  Single-electron tunneling in nanometer-scale double-barrier heterostructure devices. , 1992, Physical review. B, Condensed matter.

[36]  B. E. Kane.  A silicon-based nuclear spin quantum computer , 1998, Nature.

[37]  D. DiVincenzo,et al.  Quantum computation with quantum dots , 1997, cond-mat/9701055.

[38]  M. Devoret,et al.  Single-electron transfer in metallic nanostructures , 1992, Nature.

[39]  Xuedong Hu,et al.  Hilbert-space structure of a solid-state quantum computer: Two-electron states of a double-quantum-dot artificial molecule , 2000 .

[40]  W. V. D. Wiel,et al.  Electron transport through double quantum dots , 2002, cond-mat/0205350.

[41]  L. Vandersypen,et al.  Zeeman energy and spin relaxation in a one-electron quantum dot. , 2003, Physical review letters.

[42]  A. Abragam,et al.  Electron paramagnetic resonance of transition ions , 1970 .

[43]  C. Marcus,et al.  Detecting spin-polarized currents in ballistic nanostructures. , 2002, Physical review letters.

[44]  D. Awschalom,et al.  Semiconductor spintronics and quantum computation , 2002 .

[45]  A. Gossard,et al.  Spin-orbit coupling, antilocalization, and parallel magnetic fields in quantum dots. , 2002, Physical review letters.

[46]  I. Goodwin.  What's Gone Wrong with the SSC? It's Political, Not Technological , 1992 .