Abstract
Complete control of the state of a quantum bit (qubit) is a fundamental requirement for any quantum information processing (QIP) system. In this context, all-optical control techniques offer the advantage of a well-localized and potentially ultrafast manipulation of individual qubits in multi-qubit systems. Recently, the negatively charged silicon vacancy centre (SiV−) in diamond has emerged as a novel promising system for QIP due to its superior spectral properties and advantageous electronic structure, offering an optically accessible Λ-type level system with large orbital splittings. Here, we report on all-optical resonant as well as Raman-based coherent control of a single SiV− using ultrafast pulses as short as 1 ps, significantly faster than the centre's phonon-limited ground state coherence time of about 40 ns. These measurements prove the accessibility of a complete set of single-qubit operations relying solely on optical fields and pave the way for high-speed QIP applications using SiV− centres.
Highlights
Complete control of the state of a quantum bit is a fundamental requirement for any quantum information processing (QIP) system
For solid state qubits, which are advantageous due to their good scalability, ultrafast optical control has for example, been demonstrated in semiconductor quantum dots[2], as well as the nitrogen vacancy centre (NV) in diamond[3]
Optical control of the NV relies on the presence of a strain or electric field which lifts the orbital degeneracy in the excited state to create a V-type level configuration[3]
Summary
Complete control of the state of a quantum bit (qubit) is a fundamental requirement for any quantum information processing (QIP) system. The negatively charged silicon vacancy centre (SiV À ) in diamond has emerged as a novel promising system for QIP due to its superior spectral properties and advantageous electronic structure, offering an optically accessible L-type level system with large orbital splittings. On the other hand, implies broadband laser pulses and requires selected electronic systems: While even optical sub-cycle control[1], that is, control over time scales shorter than the qubit frequency splitting, is feasible using a single ultrafast optical pulse spanning, for example, two optical transitions in a L or V-type configuration, attention has to be paid to avoid cross-excitations of unwanted optical transitions due to the large spectral width of the pulse. These orbital states can be used to construct an SiV À based qubit even without the need of an external magnetic field and the large splitting of dg/2p 1⁄4 48 GHz in the ground and de/2p 1⁄4 259 GHz in the excited state allows for ultrafast optical coherent control
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