Demonstration of Temporal Distinguishability in a Four-Photon State and a Six-Photon State

Temporal distinguishability in Hong-Ou-Mandel interference: Generation and characterization of high-dimensional frequency entanglement

High-dimensional quantum entanglement is currently one of the most prolific fields in quantum information processing due to its high information capacity and error resilience. A versatile method for harnessing high-dimensional entanglement has long been hailed as an absolute necessity in the exploration of quantum science and technologies. Here we exploit Hong-Ou-Mandel interference to manipulate discrete frequency entanglement in arbitrary-dimensional Hilbert space. The generation and characterization of two-, four- and six-dimensional frequency entangled qudits are theoretically and experime…

一种更易于对准的 Hong-Ou-Mandel 干涉演示

An Easier-To-Align Hong-Ou-Mandel Interference Demonstration

本文提出一种利用预对准商业光纤耦合分束器简化 Hong-Ou-Mandel 干涉实验对准的方法，并使用波片通过偏振态改变光子可区分性，提供了适合本科实验室的理论描述与实验指导。

Demonstration of a 6 State-4 State Reference Frame Independent channel for Quantum Key Distribution

We study a novel protocol for reference frame independent (RFI) quantum key distribution (QKD) using six states for Alice and four states for Bob, while previous RFI protocols require a six state analyzer for Bob. Our protocol can generate a secure key for any possible phase of the entangled state, provided the variation is small compared to the measurement rate, shown by our numerical key rate analysis. We perform a proof-of-principle experiment using polarization entangled photon pairs. In the presence of a varying rotational phase, we obtain a consistently low error rate of less than $4\%$ …

Experimental high fidelity six-photon entangled state for telecloning protocols

We experimentally generate and characterize a six-photon polarization entangled state, which is usually called "Psi 6 +". This is realized with a filtering procedure of triple emissions of entangled photon pairs from a single source, which does not use any interferometric overlaps. The setup is very stable and we observe the six-photon state with high fidelity. The observed state can be used for demonstrations of telecloning and secret sharing protocols.

Experimental filtering of two-, four-, and six-photon singlets from single PDC source

Invariant entangled states remain unchanged under simultaneous identical unitary transformations of all their subsystems. We experimentally generate and characterize such invariant two-, four-, and six-photon polarization entangled states. This is done only with a suitable filtering procedure of multiple emissions of entangled photon pairs from a single source, without any interferometric overlaps. We get the desired states utilizing bosonic emission enhancement due to indistinguishability. The setup is very stable, and gives high interference contrasts. Thus, the process is a very likely cand…

在具有可忽略横向耦合的量子处理器中演示 RIP 门

Demonstration of RIP gates in a quantum processor with negligible transverse coupling

本文在六量子比特超导处理器中实验演示多模 LBI 耦合器，通过多路径干涉实现无需通量调谐的可忽略横向耦合，并以微波驱动 RIP 门实现高保真双量子比特操作。

最优无歧义四选二量子态消除的实验演示

Experimental demonstration of optimal unambiguous two-out-of-four quantum state elimination

针对非正交量子态无法完美区分的问题，本研究利用单光子四维态实现了可无歧义排除四个非正交纯态中两个的广义量子测量，错误排除率最高为3.3(2)%，验证了无误差量子态消除的可行性。

Experimental demonstration of a hyper-entangled ten-qubit Schrödinger cat state

Coherent manipulation of an increasing number of qubits for the generation of entangled states has been an important goal and benchmark in the emerging field of quantum information science. The multiparticle entangled states serve as physical resources for measurement-based quantum computing and high-precision quantum metrology. However, their experimental preparation has proved extremely challenging. To date, entangled states up to six, eight atoms, or six photonic qubits have been demonstrated. Here, by exploiting both the photons' polarization and momentum degrees of freedom, we report the …

State-independent quantum violation of noncontextuality in four dimensional space using five observables and two settings

Recently, a striking experimental demonstration [G. Kirchmair \emph{et al.}, Nature, \textbf{460}, 494(2009)] of the state-independent quantum mechanical violation of non-contextual realist models has been reported for any two-qubit state using suitable choices of \emph{nine} product observables and \emph{six} different measurement setups. In this report, a considerable simplification of such a demonstration is achieved by formulating a scheme that requires only \emph{five} product observables and \emph{two} different measurement setups. It is also pointed out that the relevant empirical data …

利用光子量子行走实验实现通用量子门和六量子比特纠缠态

Experimental realization of universal quantum gates and six-qubit entangled state using photonic quantum walk

本文利用单光子离散时间量子行走，结合偏振与路径自由度，在室温下实验实现了高保真通用量子门和六量子比特纠缠态，为量子计算提供了可扩展的新框架。

Optimal multi-photon phase sensing with a single interference fringe

Quantum entanglement can help to increase the precision of optical phase measurements beyond the shot noise limit (SNL) to the ultimate Heisenberg limit. However, the N-photon parity measurements required to achieve this optimal sensitivity are extremely difficult to realize with current photon detection technologies, requiring high-fidelity resolution of N+1 different photon distributions between the output ports. Recent experimental demonstrations of precision beyond the SNL have therefore used only one or two photon-number detection patterns instead of parity measurements. Here we investiga…