Ultra long spin coherence time for Fe3+ in ZnO: A new spin qubit

We show by means of two pulse electron spin echo experiments on Fe3+ transition metal ions in natural ZnO that their spins S = 5/2 have a spin coherence time limited at T = 6K first by instantaneous diffusion (approximate to 150 mu s), then by nuclear spectral diffusion (approximate to 450 mu s) and ultimately by spin-lattice processes (approximate to 1.4 ms). We predict a spin coherence time in the millisecond range for such a spin qubit in isotopically and chemically purified ZnO. The spin state of a single Fe3+ spin qubit could be readout by optical methods and it could be coherently manipulated using pulsed electron spin resonance (ESR) methods. A free carrier electrically gated between two nearby Fe3+ ions could efficiently couple two Fe3+ spin qubits. All those elements suggest the high potential of the Fe3+ spin qubits in ZnO for the implementation of a scalable ESR quantum computer. Copyright (C) EPLA, 2008