Xian-Min Jin

Publications (40) View all

• Article: Sequential path entanglement for quantum metrology.

  Xian-Min Jin, Cheng-Zhi Peng, Youjin Deng, Marco Barbieri, Joshua Nunn, Ian A Walmsley
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  ABSTRACT: Path entanglement is a key resource for quantum metrology. Using path-entangled states, the standard quantum limit can be beaten, and the Heisenberg limit can be achieved. However, the preparation and detection of such states scales unfavourably with the number of photons. Here we introduce sequential path entanglement, in which photons are distributed across distinct time bins with arbitrary separation, as a resource for quantum metrology. We demonstrate a scheme for converting polarization Greenberger-Horne-Zeilinger entanglement into sequential path entanglement. We observe the same enhanced phase resolution expected for conventional path entanglement, independent of the delay between consecutive photons. Sequential path entanglement can be prepared comparably easily from polarization entanglement, can be detected without using photon-number-resolving detectors, and enables novel applications.
  Scientific Reports 05/2013; 3:1779.
• Article: On-chip low loss heralded source of pure single photons

  Justin B. Spring, Patrick S. Salter, Benjamin J. Metcalf, Peter C. Humphreys, Merritt Moore, Nicholas Thomas-Peter, Marco Barbieri, Xian-Min Jin, Nathan K. Langford, W. Steven Kolthammer, Martin J. Booth, Ian A. Walmsley
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  ABSTRACT: A key obstacle to the experimental realization of many photonic quantum-enhanced technologies is the lack of low-loss sources of single photons in pure quantum states. We demonstrate a promising solution: generation of heralded single photons in a silica photonic chip by spontaneous four-wave mixing. A heralding efficiency of 40%, corresponding to a preparation efficiency of 80% accounting for detector performance, is achieved due to efficient coupling of the low-loss source to optical fibers. A single photon purity of 0.86 is measured from the source number statistics without filtering, and confirmed by direct measurement of the joint spectral intensity. We calculate that similar high-heralded-purity output can be obtained from visible to telecom spectral regions using this approach. On-chip silica sources can have immediate application in a wide range of single-photon quantum optics applications which employ silica photonics.
  04/2013;
• Article: Requirements for two-source entanglement concentration

  Mihai Vidrighin, Tim J. Bartley, Gaia Donati, Xian-Min Jin, Marco Barbieri, W. Steven Kolthammer, Animesh Datta, Ian A. Walmsley
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  ABSTRACT: Entanglement enhancement is a key task for quantum technologies. This operation performed on states produced by parametric down-conversion sources has been the object of several recent experimental investigations. In particular, conditional preparation by photon-subtraction has been shown to improve the entanglement of these states. Here we analyse the role played by non-Gaussian and Gaussian measurements in more general entanglement concentration operations performed on a pair of two-mode squeezed vacua. We find stringent requirements for achieving an improved entanglement enhancement by measuring jointly these two resource states.
  02/2013;
• Article: Direct observation of sub-binomial light

  Tim J. Bartley, Gaia Donati, Xian-Min Jin, Animesh Datta, Marco Barbieri, Ian A. Walmsley
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  ABSTRACT: Nonclassical states of light are necessary resources for quantum technologies such as cryptography, computation and the definition of metrological standards. Observing signatures of nonclassicality generally requires inferring either the photon number distribution or a quasi-probability distribution indirectly from a set of measurements. Here, we report an experiment in which the nonclassical character of families of quantum states is assessed by direct inspection of the outcomes from a multiplexed photon counter. This scheme does not register the actual photon number distribution; the statistics of the detector clicks alone serve as a witness of nonclassicality, as proposed by Sperling et al. in Phys. Rev. Lett. 109, 093601 (2012). Our work paves a way for the practical characterisation of increasingly sophisticated states and detectors.
  02/2013;
• Article: Multiphoton quantum interference in a multiport integrated photonic device.

  Benjamin J Metcalf, Nicholas Thomas-Peter, Justin B Spring, Dmytro Kundys, Matthew A Broome, Peter C Humphreys, Xian-Min Jin, Marco Barbieri, W Steven Kolthammer, James C Gates, Brian J Smith, Nathan K Langford, Peter G R Smith, Ian A Walmsley
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  ABSTRACT: Increasing the complexity of quantum photonic devices is essential for many optical information processing applications to reach a regime beyond what can be classically simulated, and integrated photonics has emerged as a leading platform for achieving this. Here we demonstrate three-photon quantum operation of an integrated device containing three coupled interferometers, eight spatial modes and many classical and nonclassical interferences. This represents a critical advance over previous complexities and the first on-chip nonclassical interference with more than two photonic inputs. We introduce a new scheme to verify quantum behaviour, using classically characterised device elements and hierarchies of photon correlation functions. We accurately predict the device's quantum behaviour and show operation inconsistent with both classical and bi-separable quantum models. Such methods for verifying multiphoton quantum behaviour are vital for achieving increased circuit complexity. Our experiment paves the way for the next generation of integrated photonic quantum simulation and computing devices.
  Nature Communications 01/2013; 4:1356. · 7.40 Impact Factor