Nanophotonic Quantum Interface for a Single Solid-state Spin

Abstract

The ability to store and transmit quantum information plays a central role in virtually all quantum information processing applications. Single spins serve as pristine quantum memories whereas photons are ideal carriers of quantum information. Strong interactions between these two systems provide the necessary interface for developing future quantum networks and distributed quantum computers.They also enable a broad range of critical quantum information functionalities such as entanglement distribution, non-destructive quantum measurements and strong photon-photon interactions. Realizing spin-photon interactions in a solid-state device is particularly desirable because it opens up the possibility of chip-integrated quantum circuits that support gigahertz bandwidth operation.In this thesis, I demonstrate a nanophotonic quantum interface between a single solid-state spin and a photon, and explore its applications in quantum information processing. First, we experimentally realize a spin-photon quantum phase switch based on a strongly coupled quantum dot and photonic crystal cavity system. This device enables coherent light-matter interactions at the fundamental limit, where a single spin controls the polarization of a photon and a single photon flips the spin state. Furthermore, we theoretically propose a way to deterministically generate spin-photon entanglement based on the spin-photon quantum interface, which is an important step towards solid-state implementations of quantum repeaters and quantum networks. Next, we show both theoretically and experimentally, a new method to optically read out a solid-state spin based on the same cavity quantum electrodynamics (QED) system. This new method achieves significant improvement in spin readout fidelity over typical approaches using fluorescence light detection.In the end, we report efforts to realize tunable and robust quantum dot based cavity QED systems. We present a technique for tuning the frequency of a quantum dot that is strongly coupled to a photonic crystal cavity by applying strain. This tuning technique enables us to accurately control the detuning between a quantum dot and a cavity without affecting other emission properties of the dot, which is essential for lots of applications associated with cavity QED systems, including non-classical light generation, photon blockade, single photon level optical switch, and also our major focus, the spin-photon quantum interface.

An integrated nanophotonic quantum register based on silicon-vacancy spins in diamond

“…In practice, nanophotonic devices also have a number of technological advantages over macroscopic optical cavities, as they can be fabricated en-masse and interfaced with on-chip electronics and photonics, making them suitable for scaling up to large-scale networks [9,14]. While strong interactions between single qubits and optical photons have been demonstrated in a number of cavity QED platforms [9,10,[15][16][17][18], no single realization currently meets all of the requirements of a quantum network node. Simultaneously achieving high-fidelity, coherent control of multiple long-lived qubits inside of a photonic structure is a major outstanding challenge.…”

An integrated diamond nanophotonics platform for quantum-optical networks

“…Despite advances in the control of microwave and optical fields using cavity and waveguide quantum electrodynamics (QED) to achieve strong interactions (4)(5)(6)(7)(8)(9), the realization of integrated quantum devices where multiple qubits are coupled by optical photons remains an outstanding challenge (10). In particular, due to their complex environments, solid-state emitters have optical transitions that generally exhibit a large inhomogeneous distribution (10,11), rapid decoherence (8) and significant spectral diffusion, especially in nanostructures (12).…”

Exciton-induced transparency in hybrid plasmonic systems

“…Strong coupling between surface plasmons in metaldielectric structures and excitons in semiconductors or dye molecules has recently attracted intense interest driven to a large extent by possible applications in ultrafast reversible switching [1][2][3], quantum computing [4,5], and light harvesting [6]. In the strong coupling regime, coherent energy echhange between excitons and plasmons [7] leads to the emergence of mixed polaritonic states with energy bands separated by an anticrossing gap (Rabi splitting) [8].…”