Publications


Efficient Classical Algorithm for Boson Sampling with Partially Distinguishable Photons.

Phys Rev Lett 120 (2018) 220502-220502

JJ Renema, A Menssen, WR Clements, G Triginer, WS Kolthammer, IA Walmsley

We demonstrate how boson sampling with photons of partial distinguishability can be expressed in terms of interference of fewer photons. We use this observation to propose a classical algorithm to simulate the output of a boson sampler fed with photons of partial distinguishability. We find conditions for which this algorithm is efficient, which gives a lower limit on the required indistinguishability to demonstrate a quantum advantage. Under these conditions, adding more photons only polynomially increases the computational cost to simulate a boson sampling experiment.


Two-Way Photonic Interface for Linking the Sr+ Transition at 422 nm to the Telecommunication C Band

Physical Review Applied 10 (2018)

TA Wright, RJA Francis-Jones, CBE Gawith, JN Becker, PM Ledingham, PGR Smith, J Nunn, PJ Mosley, B Brecht, IA Walmsley

© 2018 authors. Published by the American Physical Society. We report a single-stage bidirectional interface capable of linking Sr+ trapped-ion qubits in a long-distance quantum network. Our interface converts photons between the Sr+ emission wavelength at 422 nm and the telecom C band to enable low-loss transmission over optical fiber. We have achieved both up- and down-conversion at the single-photon level with efficiencies of 9.4% and 1.1%, respectively. Furthermore, we demonstrate noise levels that are low enough to allow for genuine quantum operation in the future.


A Noiseless Quantum Optical Memory at Room Temperature

2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE & EUROPEAN QUANTUM ELECTRONICS CONFERENCE (CLEO/EUROPE-EQEC) (2018)

PM Ledingham, KT Kaczmarek, B Brecht, A Feizpour, GS Thekkadath, SE Thomas, JHD Munns, DJ Saunders, J Nunn, IA Walmsley


High-speed noise-free optical quantum memory

PHYSICAL REVIEW A 97 (2018) ARTN 042316

KT Kaczmarek, PM Ledingham, B Brecht, SE Thomas, GS Thekkadath, O Lazo-Arjona, JHD Munns, E Poem, A Feizpour, DJ Saunders, J Nunn, IA Walmsley


All-fiber single photon sources - modal control for active routing

Optics InfoBase Conference Papers Part F111-SOF 2018 (2018)

RJA Francis-Jones, RA Hoggarth, OR Gibson, PJ Mosley

© 2018 The Author(s). Speciality fiber has enabled the development of fully-integrated heralded single-photon sources incorporating feedforward and active switching to enhance performance. We present recent results and future directions.


Conclusive experimental demonstration of one-way Einstein-Podolsky-Rosen steering

Phys. Rev. Lett. 121 (2018) 100401-100401

N Tischler, F Ghafari, TJ Baker, S Slussarenko, RB Patel, MM Weston, S Wollmann, LK Shalm, VB Verma, SW Nam, HC Nguyen, HM Wiseman, GJ Pryde

Einstein-Podolsky-Rosen steering is a quantum phenomenon wherein one party influences, or steers, the state of a distant party's particle beyond what could be achieved with a separable state, by making measurements on one half of an entangled state. This type of quantum nonlocality stands out through its asymmetric setting, and even allows for cases where one party can steer the other, but where the reverse is not true. A series of experiments have demonstrated one-way steering in the past, but all were based on significant limiting assumptions. These consisted either of restrictions on the type of allowed measurements, or of assumptions about the quantum state at hand, by mapping to a specific family of states and analysing the ideal target state rather than the real experimental state. Here, we present the first experimental demonstration of one-way steering free of such assumptions. We achieve this using a new sufficient condition for non-steerability, and, although not required by our analysis, using a novel source of extremely high-quality photonic Werner states.


Challenging local realism with human choices

NATURE 557 (2018) 212-+

C Abellan, A Acin, A Alarcon, O Alibart, CK Andersen, F Andreoli, A Beckert, FA Beduini, A Bendersky, M Bentivegna, P Bierhorst, D Burchardt, A Cabello, J Carine, S Carrasco, G Carvacho, D Cavalcanti, R Chaves, J Cortes-Vega, A Cuevas, A Delgado, H de Riedmatten, C Eichler, P Farrera, J Fuenzalida, M Garcia-Matos, R Garthoff, S Gasparinetti, T Gerrits, FG Jouneghani, S Glancy, ES Gomez, P Gonzalez, J-Y Guan, J Handsteiner, J Heinsoo, G Heinze, A Hirschmann, O Jimenez, F Kaiser, E Knill, LT Knoll, S Krinner, P Kurpiers, MA Larotonda, J-A Larsson, A Lenhard, H Li, M-H Li, G Lima, B Liu, Y Liu, IH Lopez Grande, T Lunghi, X Ma, OS Magana-Loaiza, P Magnard, A Magnoni, M Marti-Prieto, D Martinez, P Mataloni, A Mattar, M Mazzera, RP Mirin, MW Mitchell, S Nam, M Oppliger, J-W Pan, RB Patel, GJ Pryde, D Rauch, K Redeker, D Rielander, M Ringbauer, T Roberson, W Rosenfeld, Y Salathe, L Santodonato, G Sauder, T Scheidl, CT Schmiegelow, F Sciarrino, A Seri, LK Shalm, S-C Shi, S Slussarenko, MJ Stevens, S Tanzilli, F Toledo, J Tura, R Ursin, P Vergyris, VB Verma, T Walter, A Wallraff, Z Wang, H Weinfurter, MM Weston, AG White, C Wu, GB Xavier, L You, X Yuan, A Zeilinger, Q Zhang, W Zhang, J Zhong, BIGBT Collaboration


Strong Unitary and Overlap Uncertainty Relations: Theory and Experiment

PHYSICAL REVIEW LETTERS 120 (2018) ARTN 230402

K-W Bong, N Tischler, RB Patel, S Wollmann, GJ Pryde, MJW Hall


Single-photon-level interface for linking Sr<sup>+</sup>transition at 422nm with the telecommunications C-band

2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings (2018)

TA Wright, RJA Francis-Jones, CBE Gawith, JN Becker, PM Ledingham, IA Walmsley, B Brecht, J Nunn, PJ Mosley

© 2018 OSA. We present a single-stage bi-directional interface capable of linking Sr+trapped ion qubits emitting single photons at 422 nm with the telecoms C-band. We achieve external up(down) conversion efficiencies of 9.4%(1.1%).


Single-photon-level interface for linking Sr<sup>+</sup>transition at 422nm with the telecommunications C-band

Optics InfoBase Conference Papers Part F92-CLEO_AT 2018 (2018)

TA Wright, RJA Francis-Jones, CBE Gawith, JN Becker, PM Ledingham, IA Walmsley, B Brecht, J Nunn, PJ Mosley

© OSA 2018. We present a single-stage bi-directional interface capable of linking Sr+trapped ion qubits emitting single photons at 422 nm with the telecoms C-band. We achieve external up(down) conversion efficiencies of 9.4%(1.1%).


Two-Way Photonic Interface for Linking the Sr+ Transition at 422 nm to the Telecommunication C Band

PHYSICAL REVIEW APPLIED 10 (2018) ARTN 044012

TA Wright, RJA Francis-Jones, CBE Gawith, JN Becker, PM Ledingham, PGR Smith, J Nunn, PJ Mosley, B Brecht, IA Walmsley


Temporal-mode selection with a Raman quantum memory

Optics InfoBase Conference Papers Part F66-FiO 2017 (2017)

JHD Munns, SE Thomas, KT Kaczmarek, PM Ledingham, DJ Saunders, J Nunn, B Brecht, IA Walmsley

© OSA 2017. Temporal modes (TMs) of pulsed single-photon states have been identified as appealing basis states for quantum information science. Recent work has seen progress towards TM-selective operations based on nonlinear optics. Here, we demonstrate for the first time a linear TM-selective device, namely a Raman quantum memory in warm atomic Caesium vapour. We achieve switching fidelities of 86.5% when operating the memory with ns-duration pulses. These results pave the way towards new quantum information applications, where TM-selection, TM-reshaping, and network synchronisation are achieved with one single device.


Novel Interactions of Dissipative Kerr Solitons in Nonlinear Cavity Networks

2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE & EUROPEAN QUANTUM ELECTRONICS CONFERENCE (CLEO/EUROPE-EQEC) (2017)

JHD Munns, IA Walmsley, YH Wen


Temporal amplitude &amp; phase: Algorithmic reconstruction via time-domain interferometry (TeAPARTI)

Optics InfoBase Conference Papers Part F66-FiO 2017 (2017)

JHD Munns, S Park, B Brecht, IA Walmsley

© OSA 2017. We introduce a novel pulse characterisation schemeTeAPARTIwhich facilitates single-shot amplitude and phase characterisation of nanosecond duration pulses. This regime has so far been inaccessible but is crucial for optimising quantum memories. We demonstrate the generation of shaped nanosecond pulses with an electro-optic modulator and their successive characterisation with TeAPARTI.


Resource-efficient fibre-integrated temporal multiplexing of heralded single photons

JOURNAL OF OPTICS 19 (2017) ARTN 125503

RA Hoggarth, RJA Francis-Jones, PJ Mosley


Fibre-integrated noise gating of high-purity heralded single photonsE

JOURNAL OF OPTICS 19 (2017) ARTN 104005

RJA Francis-Jones, PJ Mosley


Theory of noise suppression in Lambda-type quantum memories by means of a cavity

PHYSICAL REVIEW A 96 (2017) ARTN 012338

J Nunn, JHD Munns, S Thomas, KT Kaczmarek, C Qiu, A Feizpour, E Poem, B Brecht, DJ Saunders, PM Ledingham, DV Reddy, MG Raymer, IA Walmsley


Quantum Correlations between Single Telecom Photons and a Multimode On-Demand Solid-State Quantum Memory

PHYSICAL REVIEW X 7 (2017) ARTN 021028

A Seri, A Lenhard, D Rielander, M Gundogan, PM Ledingham, M Mazzera, H de Riedmatten


A noise-free quantum memory for broadband light at room temperature

Optics InfoBase Conference Papers Part F73-QIM 2017 (2017)

KT Kaczmarek, PM Ledingham, B Brecht, A Feizpour, GS Thekkadath, SE Thomas, JHD Munns, DJ Saunders, IA Walmsley, J Nunn

© OSA 2017. We have developed a novel protocol for broadband, noise-free light-matter interactions using off-resonant two-photon absorption. We have successfully stored and retrieved 1.5 GHz bandwidth heralded single photons in warm cesium vapour, measuring a g(2)h= 0:39±0:05.


High efficiency Raman memory by suppressing radiation trapping

NEW JOURNAL OF PHYSICS 19 (2017) ARTN 063034

SED Thomas, JHD Munns, KT Kaczmarek, C Qiu, B Brecht, A Feizpour, PM Ledingham, IA Walmsley, J Nunn, DJ Saunders

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