title: Polytype control of spin qubits in silicon carbide.
abstract: Crystal defects can confine isolated electronic spins and are promising candidates for solid-state quantum information. Alongside research focusing on nitrogen-vacancy centres in diamond, an alternative strategy seeks to identify new spin systems with an expanded set of technological capabilities, a materials-driven approach that could ultimately lead to 'designer' spins with tailored properties. Here we show that the 4H, 6H and 3C polytypes of SiC all host coherent and optically addressable defect spin states, including states in all three with room-temperature quantum coherence. The prevalence of this spin coherence shows that crystal polymorphism can be a degree of freedom for engineering spin qubits. Long spin coherence times allow us to use double electron-electron resonance to measure magnetic dipole interactions between spin ensembles in inequivalent lattice sites of the same crystal. Together with the distinct optical and spin transition energies of such inequivalent states, these interactions provide a route to dipole-coupled networks of separately addressable spins.
authors: Center for Spintronics and Quantum Computation, University of California, Santa Barbara, Santa Barbara, California 93106, USA.
authors: Abram L
authors: AL
authors: Falk
authors: Bob B
authors: BB
authors: Buckley
authors: Greg
authors: G
authors: Calusine
authors: William F
authors: WF
authors: Koehl
authors: Viatcheslav V
authors: VV
authors: Dobrovitski
authors: Alberto
authors: A
authors: Politi
authors: Christian A
authors: CA
authors: Zorman
authors: Philip X-L
authors: PX
authors: Feng
authors: David D
authors: DD
authors: Awschalom
references: Nature. 2011 Nov 02;479(7371):84-7
references: 22051676
references: Phys Rev Lett. 2004 Feb 20;92(7):076401
references: 14995873
references: Science. 2006 May 26;312(5777):1191-6
references: 16614173
references: Phys Rev Lett. 2012 Jun 1;108(22):226402
references: 23003631
references: Proc Natl Acad Sci U S A. 2010 May 11;107(19):8513-8
references: 20404195
references: Phys Rev Lett. 2006 Feb 10;96(5):055501
references: 16486945
references: Science. 2012 Mar 30;335(6076):1603-6
references: 22362881
references: Appl Magn Reson. 2009 Dec;36(2-4):259-268
references: 19946596