Publications by Patrick Ledingham


A solid state spin-wave quantum memory for photonic time-Bin qubits

Optics InfoBase Conference Papers (2014)

M Gündogan, K Kutluer, PM Ledingham, M Mazzera, H de Riedmatten


A solid state spin-wave quantum memory for photonic time-Bin qubits

Optics InfoBase Conference Papers Part F3-EQEC 2015 (2014)

M Gündogan, K Kutluer, PM Ledingham, M Mazzera, H de Riedmatten


Spin-wave storage of single photon level light fields in a doped solid

Optics InfoBase Conference Papers (2013)

M Gündoǧan, D Rieländer, K Kutluer, J Fekete, PM Ledingham, M Mazzera, M Cristiani, H De Riedmatten

We present optical storage experiments with weak coherent states and heralded single photons by using the atomic frequency comb technique in the long-lived hyperfine levels in an ensemble of Pr3+ ions doped into a solid. © OSA 2013.


Hybrid optical and electronic laser locking using slow light due to spectral holes

PHYSICAL REVIEW A 87 (2013) ARTN 063824

JW Tay, WG Farr, PM Ledingham, D Korystov, JJ Longdell


Coherent storage of temporally multimode light using a spin-wave atomic frequency comb memory

NEW JOURNAL OF PHYSICS 15 (2013) ARTN 045012

M Guendogan, M Mazzera, PM Ledingham, M Cristiani, H de Riedmatten


Quantum storage of a photonic polarization qubit in a solid.

Physical review letters 108 (2012) 190504-

M Gündoğan, PM Ledingham, A Almasi, M Cristiani, H de Riedmatten

We report on the quantum storage and retrieval of photonic polarization quantum bits onto and out of a solid state storage device. The qubits are implemented with weak coherent states at the single photon level, and are stored for a predetermined time of 500 ns in a praseodymium doped crystal with a storage and retrieval efficiency of 10%, using the atomic frequency comb scheme. We characterize the storage by using quantum state tomography, and find that the average conditional fidelity of the retrieved qubits exceeds 95% for a mean photon number μ=0.4. This is significantly higher than a classical benchmark, taking into account the poissonian statistics and finite memory efficiency, which proves that our crystal functions as a quantum storage device for polarization qubits. These results extend the storage capabilities of solid state quantum light matter interfaces to polarization encoding, which is widely used in quantum information science.


Experimental realization of light with time-separated correlations by rephasing amplified spontaneous emission.

Physical review letters 109 (2012) 093602-

PM Ledingham, WR Naylor, JJ Longdell

Amplified spontaneous emission is a common noise source in active optical systems, it is generally seen as being an incoherent process. Here we excite an ensemble of rare earth ion dopants in a solid with a π pulse, resulting in amplified spontaneous emission. The application of a second π pulse leads to a coherent echo of the amplified spontaneous emission that is correlated in both amplitude and phase. For small optical thicknesses, we see evidence that the amplified spontaneous emission and its echo are entangled.


Quantum storage of a photonic polarization qubit in a solid

Physical Review Letters 108 (2012)

M Gündoǧan, PM Ledingham, A Almasi, M Cristiani, H De Riedmatten

We report on the quantum storage and retrieval of photonic polarization quantum bits onto and out of a solid state storage device. The qubits are implemented with weak coherent states at the single photon level, and are stored for a predetermined time of 500 ns in a praseodymium doped crystal with a storage and retrieval efficiency of 10%, using the atomic frequency comb scheme. We characterize the storage by using quantum state tomography, and find that the average conditional fidelity of the retrieved qubits exceeds 95% for a mean photon number μ=0.4. This is significantly higher than a classical benchmark, taking into account the Poissonian statistics and finite memory efficiency, which proves that our crystal functions as a quantum storage device for polarization qubits. These results extend the storage capabilities of solid state quantum light matter interfaces to polarization encoding, which is widely used in quantum information science. © 2012 American Physical Society.


Quantum Correlations using Strong Optical Pulses in Rare Earth Ion Doped Crystals

2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) (2011)

PM Ledingham, JJ Longdell, IEEE


Quantum correlations using strong optical pulses in rare earth ion doped crystals

Optics InfoBase Conference Papers (2011)

PM Ledingham, JJ Longdell

We use photon echo based protocols with cryogenic rare earth ion dopants to create photon streams with time separated correlations. Theoretically, these streams are non-classically correlated. We present progress toward realizing this correlation. © 2010 Optical Society of America.


Quantum correlations using strong optical pulses in rare earth ion doped crystals

Optics InfoBase Conference Papers (2011)

PM Ledingham, JJ Longdell

We use photon echo based protocols with cryogenic rare earth ion dopants to create photon streams with time separated correlations. Theoretically, these streams are non-classically correlated. We present progress toward realizing this correlation. © 2010 Optical Society of America.


Photon-echo quantum memories in inhomogeneously broadened two-level atoms

PHYSICAL REVIEW A 84 (2011) ARTN 022309

DL McAuslan, PM Ledingham, WR Naylor, SE Beavan, MP Hedges, MJ Sellars, JJ Longdell


Quantum correlations using strong optical pulses in rare earth ion doped crystals

2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011 (2011)

PM Ledingham, JJ Longdell

We use photon echo based protocols with cryogenic rare earth ion dopants to create photon streams with time separated correlations. Theoretically, these streams are non-classically correlated. We present progress toward realizing this correlation. © 2011 OSA.


Photon echo without a free induction decay in a double-Λ system.

Optics letters 36 (2011) 1272-1274

SE Beavan, PM Ledingham, JJ Longdell, MJ Sellars

We have characterized a novel photon-echo pulse sequence for a double-Λ-type energy level system where the input and rephasing transitions are different from the applied π pulses. We show that, despite having imperfect π-pulses associated with large coherent emission due to free induction decay (FID), the noise added in the echo mode is only 0.2 ± 0.1 photons per shot, compared to 4 × 10⁴ photons in the FID modes. Using this echo pulse sequence in the "rephased amplified spontaneous emission" (RASE) scheme [Phys. Rev. A 81, 012301 (2010)] will allow for generation of entangled photon pairs that are in different frequency, temporal, and potentially spatial modes to any bright driving fields. The coherence and efficiency properties of this sequence were characterized in a Pr(3+):Y₂SiO₅ crystal.


Coherent detection of ultrasound using spectral hole burning media

ADVANCES IN PHOTONICS OF QUANTUM COMPUTING, MEMORY, AND COMMUNICATION IV 7948 (2011)

JW Tay, PM Ledingham, JJ Longdell


Coherent optical ultrasound detection with rare-earth ion dopants.

Applied optics 49 (2010) 4331-4334

JW Tay, PM Ledingham, JJ Longdell

We describe theoretical and experimental demonstration for optical detection of ultrasound using a spectral hole engraved in cryogenically cooled rare-earth ion-doped solids. Our method utilizes the dispersion effects due to the spectral hole to perform phase-to-amplitude modulation conversion. Like previous approaches using spectral holes, it has the advantage of detection with large étendue. The method also has the benefit that high sensitivity can be obtained with moderate absorption contrast for the spectral holes.


Nonclassical photon streams using rephased amplified spontaneous emission

PHYSICAL REVIEW A 81 (2010) ARTN 012301

PM Ledingham, WR Naylor, JJ Longdell, SE Beavan, MJ Sellars

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