Long-lived spin coherence in silicon with electrical readout Gavin W Morley London Centre for Nanotechnology and Depar

1. Long-lived spin coherence in silicon with electrical readout Gavin W Morley London Centre for Nanotechnology and Department of Physics and Astronomy, UCL Funding: Quantum Coherent Properties of Spins II, PITP, 6th December 2009

2. Introduction People Involved in this Work University of Utah Christoph Boehme Dane R McCamey Heather A Seipel National High Magnetic Field Laboratory Hans van Tol Louis-Claude Brunel

3. Introduction Phosphorus dopants in silicon - Long spin coherence (A M Tyryshkin et al, PRB 68, 193207 2003) - Atomic positioning (S R Schofield et al, PRL 91, 136104 2003) - Control wavefunction size (N Q Vinh et al, PNAS 105, 10649 2008)

4. Introduction Introduction Our research Towards quantum computing Experimental challenges: • Initialization • Control superposition and entanglement • Decoherence • Readout we have a plan

5. Introduction Our research Pulsed ESR at 4, 8 and 12 T GWM, L-C Brunel and J van Tol, Rev Sci Instrum 79, 064703 (2008) Nuclear Spin Polarization: GWM, J van Tol, A Ardavan, K Porfyrakis, J Zhang and G A D Briggs, Phys Rev Lett 98, 220501 (2007) CW ESR: J van Tol, L C Brunel and R J Wylde, Rev Sci Inst 76, 074101 (2005)

6. Introduction Our research Visible light creates electron-hole pairs Circularly polarized 240 GHz radiation manipulates electron spins 10 micron DC current source reacts slowly 1 mm overlap Fast current detector measures signal A silicon B0 = 8.6 T T = 2.8 K

7. Introduction Our research Continuous-wave electrically-detected magnetic resonance Our papers: PRL 101, 207602 (2008), PRL 102, 027601 (2009), PRB 78, 045303 (2008)

8. Introduction Our research Visible light creates electron-hole pairs Circularly polarized 240 GHz radiation manipulates electron spins DC current source reacts slowly 1 mm overlap Fast current detector measures signal A silicon B0 = 8.6 T T = 2.8 K 10 micron

9. Introduction Our research Circularly polarized 240 GHz radiation manipulates electron spins e e e Visible light creates electron-hole pairs h h DD Thornton & A Honig, PRL 30 909 (1973) A Honig & M Moroz, RSI 49 183 (1978) GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602, (2008) B0 = 8.6 T T = 2.8 K 10 micron Sensitivity: need (100 nm)3 sample

10. Introduction Our research Continuous-wave electrically-detected magnetic resonance Our papers: PRL 101, 207602 (2008), PRL 102, 027601 (2009), PRB 78, 045303 (2008)

11. Introduction Our research Continuous-wave electrically-detected magnetic resonance Our papers: PRL 101, 207602 (2008), PRL 102, 027601 (2009), PRB 78, 045303 (2008) DR McCamey, J van Tol, GWM & C. Boehme, PRL 102, 027601 (2009)

12. Introduction Our research Continuous-wave electrically-detected magnetic resonance P = 0 P < 0 • Thermal Equilibrium • Flip-flop, GX • Capture-emission, GCE • Thermal Equilibrium • Flip-flop, GX • Thermal Equilibrium Our papers: PRL 101, 207602 (2008), PRL 102, 027601 (2009), PRB 78, 045303 (2008) DR McCamey, J van Tol, GWM & C. Boehme, PRL 102, 027601 (2009)

13. Introduction Our research Continuous-wave electrically-detected magnetic resonance Our papers: PRL 101, 207602 (2008), PRL 102, 027601 (2009), PRB 78, 045303 (2008)

14. Introduction Our research Transient response to a 240 GHz pulse GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

15. Introduction Our research Rabi Oscillations Isidor Isaac Rabi (1898 – 1988) GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

16. Introduction Our research Rabi Oscillations GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

17. Introduction Our research Spin echo Erwin L Hahn (born 1921) Spin echo animation by Chris Noble GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

18. Introduction Our research Electrically-detected spin echo GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

19. Introduction Our research Decay of electrically-detected spin echoes GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

20. Introduction Our research Decay of electrically-detected spin echoes GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

21. Introduction Our research Decay of electrically-detected spin echoes GWM, DR McCamey, HA Seipel, LC Brunel, J van Tol & C. Boehme, PRL 101, 207602 (2008)

22. Introduction Our research Entangling multiple qubits: theory A M Stoneham, A J Fisher & P T Greenland, J Phys CM 15 L477 (2003) R Rodriquez, A J Fisher, P T Greenland & A M Stoneham, J Phys CM 16 2757 (2004) A M Stoneham, A H Harker & GWM, in press at J Phys CM, arXiv:0904.4895 Qubit 1 Control Qubit 2 light

23. Introduction Our research Entangling multiple qubits Bismuth is a good as phosphorus

24. Introduction Our research Conclusions and future work Conclusions Experimental challenges: • Initialization • Control superposition and entanglement • Decoherence • Readout we have a plan