Quantum information in silicon: Initialization, manipulation, storage and readout

Spin qubits in silicon are exciting because of their long coherence times [1] and the electrical readout of the state of one electron spin [2]. In a single experiment we demonstrate initialization [3], manipulation, storage and electrical readout of quantum information with a small ensemble of phosphorus electronic and nuclear spins in silicon [4]. Our electrical readout does not destroy the electron spin coherence which is limited instead by naturally-occurring $^{29}$Si nuclear spins. These experiments require a pulsed electron spin resonance spectrometer operating at high magnetic fields [5]. Silicon quantum computers would benefit from having a second dopant species which can be addressed selectively [6-8], and we find that bismuth atoms are well suited for this role [9]. They offer long spin coherence times [9,10] as well as new opportunities [11] when compared with phosphorus. \\[4pt] [1] A M Tyryshkin {\&} S A Lyon, Phosphorus electron spin coherence time can be over 10 s, Private communication (2010) \newline [2] A Morello\textit{ et al}, Nature \textbf{467}, 687 (2010) \newline [3] D R McCamey, J van Tol, G W Morley {\&} C Boehme, Phys Rev Lett \textbf{102}, 027601 (2009) \newline [4] G W Morley\textit{ et al}, Phys Rev Lett \textbf{101}, 07602 (2008) \newline [5] G W Morley, L-C Brunel {\&} J van Tol, Rev Sci Instrum \textbf{79}, 064703 (2008) \newline [6] A M Stoneham, A H Harker {\&} G W Morley, J Phys Condens Matter \textbf{21}, 364222 (2009) \newline [7] A M Stoneham, A J Fisher {\&} P T Greenland, J Phys Condens Matter \textbf{15}, L447 (2003) \newline [8] P T Greenland\textit{ et al}, Nature \textbf{465}, 1057 (2010) \newline [9] G W Morley\textit{ et al}, Nature Mater \textbf{9}, 725 (2010) \newline [10] R E George\textit{ et al}, Phys Rev Lett \textbf{105}, 067601 (2010) \newline [11] M H Mohammady, G W Morley {\&} T S Monteiro, Phys Rev Lett \textbf{105}, 067602 (2010)