Experimental verification of the feasibility of a quantum channel between Space and Earth

Feasibility Assessment For Practical Continuous Variable Quantum Key Distribution Over The Satellite-to-Earth Channel

Currently, quantum key distribution (QKD) using continuous variable (CV) technology has only been demonstrated over short-range terrestrial links. Here we attempt to answer whether CV-QKD over the much longer satellite-to-Earth channel is feasible. To this end, we first review the concepts and technologies that will enable CV-QKD over the satellite-to-Earth channels. We then consider, in the infinite key limit, the simplest-to-deploy QKD protocols, the coherent state (CS) QKD protocol with homodyne detection and the CS-QKD protocol with heterodyne detection. We then focus on the CS-QKD protoco…

复杂系统中的量子计量学及量子模拟实验验证

Quantum metrology in complex systems and experimental verification by quantum simulation

本文回顾了复杂系统中基于量子纠缠与相干的量子计量方案，并探讨了利用量子模拟实验验证其可行性及展示束缚态、单光子开关等物理现象。

Experimental preparation and verification of quantum money

A quantum money scheme enables a trusted bank to provide untrusted users with verifiable quantum banknotes that cannot be forged. In this work, we report an experimental demonstration of the preparation and verification of unforgeable quantum banknotes. We employ a security analysis that takes experimental imperfections fully into account. We measure a total of $3.6\times 10^6$ states in one verification round, limiting the forging probability to $10^{-7}$ based on the security analysis. Our results demonstrate the feasibility of preparing and verifying quantum banknotes using currently availa…

Robust quantum gates and a bus architecture for quantum computing with rare-earth-ion doped crystals

We present a composite pulse controlled phase gate which together with a bus architecture improves the feasibility of a recent quantum computing proposal based on rare-earth-ion doped crystals. Our proposed gate operation is tolerant to variations between ions of coupling strengths, pulse lengths, and frequency shifts, and it achieves worst case fidelities above 0.999 with relative variations in coupling strength as high as 10% and frequency shifts up to several percent of the resonant Rabi frequency of the laser used to implement the gate. We outline an experiment to demonstrate the creation …

Schemes for robust quantum computation with polar molecules: analysis of experimental feasibility

We analyse recently proposed physical implementations of a quantum computer based on polar molecules. A set of general requirements for a molecular system is presented, which would provide an optimal combination of quantum gate times, coherence times, number of operations, high gate accuracy and experimental feasibility. We proceed with a detailed analysis of a scheme utilizing switchable dipole-dipole interactions between polar molecules. Switchable dipole-dipole interaction is an efficient tool for realization of two-qubit quantum gates, necessary to construct a universal set of gates. We co…

All-optical preparation of coherent dark states of a single rare earth ion spin in a crystal

All-optical addressing and control of single solid-state based qubits allows for scalable architectures of quantum devices such as quantum networks and quantum simulators. So far, all-optical addressing of qubits was demonstrated only for color centers in diamond and quantum dots. Here, we demonstrate generation of coherent dark state of a single rare earth ion in a solid, namely a cerium ion in yttrium aluminum garnet (YAG). The dark state was formed under the condition of coherent population trapping. Furthermore, high-resolution spectroscopic studies of native and implanted single Ce ions h…