Xing-Can Yao

Observation of eight-photon entanglement

Researchers demonstrate the creation of an eight-photon Schrodinger-cat state with genuine multipartite entanglement by developing noise-reduction multiphoton interferometer and post-selection detection. The ability to control eight individual photons will enable new multiphoton entanglement experiments in previously inaccessible parameter regimes.

Experimental demonstration of a hyper-entangled ten-qubit Schr|[ouml]|dinger cat state

Creating entangled photon states becomes technologically ever more difficult as the number of particles increases, and the current record stands at six entangled photons. However, using both their polarization and momentum degrees of freedom, up to ten-qubit states can be encoded in ‘only’ five photons, as has now been demonstrated.

Experimental demonstration of topological error correction

Scalable quantum computing can be achieved only if quantum bits are manipulated in a fault-tolerant fashion. Topological error correction—a method that combines topological quantum computation with quantum error correction—has the highest known tolerable error rate for a local architecture. The technique makes use of cluster states with topological properties and requires only nearest-neighbour interactions. Here we report the experimental demonstration of topological error correction with an eight-photon cluster state. We show that a correlation can be protected against a single error on any quantum bit. Also, when all quantum bits are simultaneously subjected to errors with equal probability, the effective error rate can be significantly reduced. Our work demonstrates the viability of topological error correction for fault-tolerant quantum information processing.

Experimental Realization of a Controlled-NOT Gate with Four-Photon Six-Qubit Cluster States

We experimentally demonstrate an optical controlled-NOT (CNOT) gate with arbitrary single inputs based on a 4-photon 6-qubit cluster state entangled both in polarization and spatial modes. We first generate the 6-qubit state, and then, by performing single-qubit measurements, the CNOT gate is applied to arbitrary single input qubits. To characterize the performance of the gate, we estimate its quantum process fidelity and prove its entangling capability. In addition, our results show that the gate cannot be reproduced by local operations and classical communication. Our experiment shows that such hyper-entangled cluster states are promising candidates for efficient optical quantum computation.

Observation of Coupled Vortex Lattices in a Mass-Imbalance Bose and Fermi Superfluid Mixture.

Quantized vortices play an essential role in diverse superfluid phenomena. In a Bose-Fermi superfluid mixture, especially of two mass-imbalance species, such macroscopic quantum phenomena are particularly rich due to the interplay between the Bose and Fermi superfluidity. However, generating a Bose-Fermi two-species superfluid, producing coupled vortex lattices within, and further probing interspecies interaction effects remain challenging. Here, we experimentally realize a two-species superfluid with dilute gases of lithium-6 and potassium-41, having a mass ratio of about seven. By rotating the superfluid mixture, we simultaneously produce coupled vortex lattices of the two species and thus present a definitive visual evidence for the double superfluidity. Moreover, we report several unconventional behaviors, due to the Bose-Fermi interaction, on the formation and decay of two-species vortices.

Implementation of a measurement-device-independent entanglement witness.

Entanglement, the essential resource in quantum information processing, should be witnessed in many tasks such as quantum computing and quantum communication. The conventional entanglement witness method, relying on an idealized implementation of measurements, could wrongly conclude a separable state to be entangled due to imperfect detections. Inspired by the idea of a time-shift attack, we construct an attack on the conventional entanglement witness process and demonstrate that a separable state can be falsely identified to be entangled. To close such detection loopholes, based on a recently proposed measurement-device-independent entanglement witness method, we design and experimentally demonstrate a measurement-device-independent entanglement witness for a variety of two-qubit states. By the new scheme, we show that an entanglement witness can be realized without detection loopholes.

Observation of ten-photon entanglement using thin BiB 3 O 6 crystals

Coherently manipulating a number of entangled qubits is the key task of quantum information processing. In this paper, we report on the experimental realization of a ten-photon Greenberger–Horne–Zeilinger state using thin BiB3O6 crystals. The observed fidelity is 0.606±0.029, demonstrating a genuine entanglement with a standard deviation of 3.6σ. This result is further verified using p-value calculation, obtaining an upper bound of 3.7×10−3 under an assumed hypothesis test. Our experiment paves a new way to efficiently engineer BiB3O6 crystal-based multi-photon entanglement systems, which provides a promising platform for investigating advanced optical quantum information processing tasks such as boson sampling, quantum error correction, and quantum-enhanced measurement.

Production of largeK41Bose-Einstein condensates usingD1gray molasses

We use D1 gray molasses to achieve Bose-Einstein condensation of a large number of

Experimental quantum channel simulation

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Experimental measurement-based quantum computing beyond the cluster-state model

K atoms in an optical dipole trap. By combining a new configuration of compressed-MOT with D1 gray molasses, we obtain a cold sample of