Coherent interference effects in a nano-assembled optical cavity-QED system

Direct observation of nanofabrication influence on the optical properties of single self-assembled InAs/GaAs quantum dots

Single self-assembled InAs/GaAs quantum dots are a promising solid-state quantum technology, with which vacuum Rabi splitting, single-photon-level nonlinearities, and bright, pure, and indistinguishable single-photon generation having been demonstrated. For such achievements, nanofabrication is used to create structures in which the quantum dot preferentially interacts with strongly-confined optical modes. An open question is the extent to which such nanofabrication may also have an adverse influence, through the creation of traps and surface states that could induce blinking, spectral diffusi…

Photostable single-photon emission from self-assembled nanocrystals of polycyclic aromatic hydrocarbons

Quantum technologies could largely benefit from the control of quantum emitters in sub-micrometric size crystals. These are naturally prone to the integration in hybrid devices, including heterostructures and complex photonic devices. Currently available quantum emitters sculpted in nanocrystals suffer from spectral instability, preventing their use as single photon sources e.g., for most quantum optics operations. In this work we report on unprecedented performances of single-photon emission from organic nanocrystals (average size of hundreds \SI{}{\nano\meter}), made of anthracene (Ac) and d…

Cavity-QED models of switches for attojoule-scale nanophotonic logic

Quantum optical input-output models are described for a class of optical switches based on cavity quantum electrodynamics (cavity QED) with a single multilevel atom (or comparable bound system of charges) coupled simultaneously to several resonant field modes. A recent limit theorem for quantum stochastic differential equations is used to show that such models converge to a simple scattering matrix in a type of strong coupling limit that seems natural for nanophotonic systems. Numerical integration is used to show that the behavior of the pre-limit model approximates that of the simple scatter…

A Self Assembled Nanoelectronic Quantum Computer Based on the Rashba Effect in Quantum Dots

Quantum computers promise vastly enhanced computational power and an uncanny ability to solve classically intractable problems. However, few proposals exist for robust, solid state implementation of such computers where the quantum gates are sufficiently miniaturized to have nanometer-scale dimensions. Here I present a new approach whereby a complete computer with nanoscale gates might be self-assembled using chemical synthesis. Specifically, I demonstrate how to self-assemble the fundamental unit of this quantum computer - a 2-qubit universal quantum controlled-NOT gate - based on two exchang…

Macroscopic QED for quantum nanophotonics: Emitter-centered modes as a minimal basis for multi-emitter problems

We present an overview of the framework of macroscopic quantum electrodynamics from a quantum nanophotonics perspective. Particularly, we focus our attention on three aspects of the theory which are crucial for the description of quantum optical phenomena in nanophotonic structures. First, we review the light-matter interaction Hamiltonian itself, with special emphasis on its gauge independence and the minimal and multipolar coupling schemes. Second, we discuss the treatment of the external pumping of quantum-optical systems by classical electromagnetic fields. Third, we introduce an exact, co…

Continuous quantum non-demolition measurement of Fock states of a nanoresonator using feedback-controlled circuit QED

We propose a scheme for the quantum non-demolition (QND) measurement of Fock states of a nanomechanical resonator via feedback control of a coupled circuit QED system. A Cooper pair box (CPB) is coupled to both the nanoresonator and microwave cavity. The CPB is read-out via homodyne detection on the cavity and feedback control is used to effect a non-dissipative measurement of the CPB. This realizes an indirect QND measurement of the nanoresonator via a second-order coupling of the CPB to the nanoresonator number operator. The phonon number of the Fock state may be determined by integrating th…

Analogue of Cavity QED for Coupling between Spin and Nanomechanical Resonator

We describe a cavity QED analogue for the coupling system of a spin and a nanomechanical resonator with a magnetic tip. For the quantized nanomechanical resonator, a spin-boson model for this coupling system can refer to a Jaynes-Cummings(JC) or an anti-JC model. These observations predict some quantum optical phenomena, such as squeezing and "collapse-revival" in the single oscillation mode of the nanomechanical resonator when it is initially prepared in the quasi-classical state. By modulating the phase of RF magnetic field one can switch the system between the JC and anti-JC model, which pr…

Manipulating nanoscale atom-atom interactions with cavity QED

We theoretically explore manipulation of interactions between excited and ground state atoms at nanoscale separations by cavity quantum electrodynamics (CQED). We develop an adiabatic molecular dressed state formalism and show that it is possible to generate Fano-Feshbach resonances between ground and long-lived excited-state atoms inside a cavity. The resonances are shown to arise due to non-adiabatic coupling near a pseudo-crossing between the dressed state potentials. We illustrate our results with a model study using fermionic $^{171}$Yb atoms in a two-modal cavity. Our study is important …

解决许多体纳米纤维腔量子电动力学系统中无串扰量子门操作的要求

Addressing requirements for crosstalk-free quantum-gate operation in many-body nanofiber cavity QED systems

本文提出了一种基于光纤的量子计算平台，通过优化光-物质耦合实现无串扰量子门操作，并分析了其理论最优性能。

Cavity QED with hybrid nanocircuits: from atomic-like physics to condensed matter phenomena

Circuit QED techniques have been instrumental to manipulate and probe with exquisite sensitivity the quantum state of superconducting quantum bits coupled to microwave cavities. Recently, it has become possible to fabricate new devices where the superconducting quantum bits are replaced by hybrid mesoscopic circuits combining nanoconductors and metallic reservoirs. This mesoscopic QED provides a new experimental playground to study the light-matter interaction in electronic circuits. Here, we present the experimental state of the art of Mesoscopic QED and its theoretical description. A first c…

通过灰度光刻在更低温度下制造空气桥以提高电路 QED 量子处理器中纳米线 transmon 的良率

Lower-temperature fabrication of airbridges by grayscale lithography to increase yield of nanowire transmons in circuit QED quantum processors

针对高温空气桥工艺会损害预置 Josephson 元件的问题，本文用灰度光刻替代光刻胶回流，将峰值温度由200°C降至150°C，显著提高了Al接触InAs纳米线transmon量子比特的良率。

超高相干自组装金刚石纳米机械系统揭示超流动力学

Ultracoherent self-assembled diamond nanomechanics reveals superfluid dynamics

超高相干自组装金刚石纳米机械系统揭示超流动力学，通过应变工程实现超低声学损耗，探测残余耗散并揭示三种双能级系统通道和一个拓扑耗散通道。