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Sunny start to the new semester (April 2023). Show image information

Sunny start to the new semester (April 2023).

Photo: Paderborn University, Besim Mazhiqi

Prof. Dr. Tim Bartley

Contact
Biography
Publications
Prof. Dr. Tim Bartley

Mesoscopic Quantum Optics

Head - Professor

Phone:
+49 5251 60-5881
Office:
P8.3.13
Visitor:
Pohlweg 47-49
33098 Paderborn
Prof. Dr. Tim Bartley
Science Career
Since 2022

Professor (W2)

Paderborn University, Germany

2015 - 2022

Junior Professor (W1)

Paderborn University, Germany

08/2021 - 01/2022

Parental leave (part time)

05/2021 - 07/2021

Parental leave

2014 - 2015

Postdoc

National Institute for Standards and Technology, Boulder, Colorado, USA

2013 - 2014

Postdoc

Oxford University, UK

Training
28.03.2014

Doctorate

DPhil, Atomic & Laser Physics, Oxford University, UK
Supervisor: Prof. Dr. Ian A. Walmsley

2005 - 2009

Degree programme

MSci Physics with a year in Europe, Imperial College, London, UK

2007 - 2008

Degree programme

Erasmus Year abroad, FAU Erlangen Nürnberg, Erlangen, Germany

Supporting Activities
Since 2015

Supervision of Researchers in Early Career Phases

Distinguished Master Student

Moritz Bartnick, Bachelor & Masters student (2016 – 2020): now Marie Curie PhD Fellow, EPFL
 

Doctorates
Completed doctorates: 1, ongoing doctorates: 6

Dr. Jan Philipp Höpker, 2022: now Postdoc at Paderborn University, Germany
 

Postdocs
Total: 3, currently 2 postdocs

Selected examples:

Dr. Evan Meyer-Scott, Postdoc (2016 – 2018): now Director, Quantum Processors, Photonic Inc, Canada

Dr. Stephan Krapick, Postdoc (2015 – 2016): now System Architect, Behr-Hella Thermocontrol, Germany

Recognitions
2022

ERC Starting Grant, European Commission

2018

BMBF Quantum Future Junior Group Leader, Germany

2014

DAAD Postdoctoral Research International Mobility Experience (PRIME) Fellow, Germany

2008

Imperial College, London Ken Allen Prize for Academic Excellence, UK

Scientific Engagement
Board Activities
Since 2016

Board member, Center for Optoelectronics and Photonics Paderborn (CeOPP), Paderborn University

2019 - 2021

Elected Representative of the Faculty of Natural Sciences, Committee for Research and Junior Academics, Paderborn University

Organization of Scientific Events
Since 2022

CLEO Subcommittee Chair, S&I 15: Quantum and Atomic Devices & Instrumentation

Since 2021

Selected Invited Talks

2022: International Workshop on Physical Computing, Sicily

2021: SPIE Photonics West (online)

2021: Q.Link.X Seminar, Bad Honnef

Since 2015

Selected Outreach Activities

2023: World Quantum Day

2022: Public “Evening Colloquium” on the Nobel Prize in Physics 2022

Since 2021: MINT-EC Day: Laser Physics

Since: 2015: Hosting regular school visits, work-experience students, lab tours and open days

2020 - 2021

CLEO Subcommittee Member, FS3: Quantum Photonics

2019

Scientific and local organising committee member, Central European Workshop on Quantum Optics (CEWQO) 2019

2018

Lead organiser, 683rd WE-Heraeus Seminar: "Physics and Applications of Superconducting Nanowire Single Photon Detectors"

Memberships
Since 2018

Founding member of the Institute for Photonic Quantum Systems, PhoQS, Paderborn University

Expert Activities
Since 2016

Funding Reviewer: DFG; Clusters4Future; TALENT Doctoral Program, University of Copenhagen; Canada Research Chair

Since 2012

Journal Referee: Nature Group, APS, AIP, Optica Group

Since 2022

CLEO Subcommittee Chair, S&I 15: Quantum and Atomic Devices & Instrumentation

Organization of Scientific Events
Since 2022

Professor (W2)

Paderborn University, Germany

Science Career
Since 2021

Selected Invited Talks

2022: International Workshop on Physical Computing, Sicily

2021: SPIE Photonics West (online)

2021: Q.Link.X Seminar, Bad Honnef

Organization of Scientific Events
Since 2018

Founding member of the Institute for Photonic Quantum Systems, PhoQS, Paderborn University

Memberships
Since 2016

Funding Reviewer: DFG; Clusters4Future; TALENT Doctoral Program, University of Copenhagen; Canada Research Chair

Expert Activities
Since 2016

Board member, Center for Optoelectronics and Photonics Paderborn (CeOPP), Paderborn University

Board Activities
Since 2015

Selected Outreach Activities

2023: World Quantum Day

2022: Public “Evening Colloquium” on the Nobel Prize in Physics 2022

Since 2021: MINT-EC Day: Laser Physics

Since: 2015: Hosting regular school visits, work-experience students, lab tours and open days

Organization of Scientific Events
Since 2015

Supervision of Researchers in Early Career Phases

Distinguished Master Student

Moritz Bartnick, Bachelor & Masters student (2016 – 2020): now Marie Curie PhD Fellow, EPFL
 

Doctorates
Completed doctorates: 1, ongoing doctorates: 6

Dr. Jan Philipp Höpker, 2022: now Postdoc at Paderborn University, Germany
 

Postdocs
Total: 3, currently 2 postdocs

Selected examples:

Dr. Evan Meyer-Scott, Postdoc (2016 – 2018): now Director, Quantum Processors, Photonic Inc, Canada

Dr. Stephan Krapick, Postdoc (2015 – 2016): now System Architect, Behr-Hella Thermocontrol, Germany

Supporting Activities
Since 2012

Journal Referee: Nature Group, APS, AIP, Optica Group

Expert Activities
2022

ERC Starting Grant, European Commission

Recognitions
2015 - 2022

Junior Professor (W1)

Paderborn University, Germany

Science Career
08/2021 - 01/2022

Parental leave (part time)

Science Career
05/2021 - 07/2021

Parental leave

Science Career
2020 - 2021

CLEO Subcommittee Member, FS3: Quantum Photonics

Organization of Scientific Events
2019 - 2021

Elected Representative of the Faculty of Natural Sciences, Committee for Research and Junior Academics, Paderborn University

Board Activities
2019

Scientific and local organising committee member, Central European Workshop on Quantum Optics (CEWQO) 2019

Organization of Scientific Events
2018

BMBF Quantum Future Junior Group Leader, Germany

Recognitions
2018

Lead organiser, 683rd WE-Heraeus Seminar: "Physics and Applications of Superconducting Nanowire Single Photon Detectors"

Organization of Scientific Events
2014 - 2015

Postdoc

National Institute for Standards and Technology, Boulder, Colorado, USA

Science Career
28.03.2014

Doctorate

DPhil, Atomic & Laser Physics, Oxford University, UK
Supervisor: Prof. Dr. Ian A. Walmsley

Training
2014

DAAD Postdoctoral Research International Mobility Experience (PRIME) Fellow, Germany

Recognitions
2013 - 2014

Postdoc

Oxford University, UK

Science Career
2005 - 2009

Degree programme

MSci Physics with a year in Europe, Imperial College, London, UK

Training
2008

Imperial College, London Ken Allen Prize for Academic Excellence, UK

Recognitions
2007 - 2008

Degree programme

Erasmus Year abroad, FAU Erlangen Nürnberg, Erlangen, Germany

Training

Open list in Research Information System

2023

Nanosecond gating of superconducting nanowire single-photon detectors using cryogenic bias circuitry

T. Hummel, A. Widhalm, J.P. Höpker, K. Jöns, J. Chang, A. Fognini, S. Steinhauer, V. Zwiller, A. Zrenner, T. Bartley, Optics Express (2023), 31(1), 610

<jats:p>Superconducting nanowire single-photon detectors (SNSPDs) show near unity efficiency, low dark count rate, and short recovery time. Combining these characteristics with temporal control of SNSPDs broadens their applications as in active de-latching for higher dynamic range counting or temporal filtering for pump-probe spectroscopy or LiDAR. To that end, we demonstrate active gating of an SNSPD with a minimum off-to-on rise time of 2.4 ns and a total gate length of 5.0 ns. We show how the rise time depends on the inductance of the detector in combination with the control electronics. The gate window is demonstrated to be fully and freely, electrically tunable up to 500 ns at a repetition rate of 1.0 MHz, as well as ungated, free-running operation. Control electronics to generate the gating are mounted on the 2.3 K stage of a closed-cycle sorption cryostat, while the detector is operated on the cold stage at 0.8 K. We show that the efficiency and timing jitter of the detector is not altered during the on-time of the gating window. We exploit gated operation to demonstrate a method to increase in the photon counting dynamic range by a factor 11.2, as well as temporal filtering of a strong pump in an emulated pump-probe experiment.</jats:p>


Compact Metasurface-Based Optical Pulse-Shaping Device

R. Geromel, P. Georgi, M. Protte, S. Lei, T. Bartley, L. Huang, T. Zentgraf, Nano Letters (2023), 23(8), pp. 3196 - 3201

Dispersion is present in every optical setup and is often an undesired effect, especially in nonlinear-optical experiments where ultrashort laser pulses are needed. Typically, bulky pulse compressors consisting of gratings or prisms are used to address this issue by precompensating the dispersion of the optical components. However, these devices are only able to compensate for a part of the dispersion (second-order dispersion). Here, we present a compact pulse-shaping device that uses plasmonic metasurfaces to apply an arbitrarily designed spectral phase delay allowing for a full dispersion control. Furthermore, with specific phase encodings, this device can be used to temporally reshape the incident laser pulses into more complex pulse forms such as a double pulse. We verify the performance of our device by using an SHG-FROG measurement setup together with a retrieval algorithm to extract the dispersion that our device applies to an incident laser pulse.


2022

A Versatile Metasurface Enabling Superwettability for Self‐Cleaning and Dynamic Color Response

J. Lu, B. Sain, P. Georgi, M. Protte, T. Bartley, T. Zentgraf, Advanced Optical Materials (2022), 10(1), 2101781

Metasurfaces provide applications for a variety of flat elements and devices due to the ability to modulate light with subwavelength structures. The working principle meanwhile gives rise to the crucial problem and challenge to protect the metasurface from dust or clean the unavoidable contaminants during daily usage. Here, taking advantage of the intelligent bioinspired surfaces which exhibit self-cleaning properties, a versatile dielectric metasurface benefiting from the obtained superhydrophilic or quasi-superhydrophobic states is shown. The design is realized by embedding the metasurface inside a large area of wettability supporting structures, which is highly efficient in fabrication, and achieves both optical and wettability functionality at the same time. The superhydrophilic state enables an enhanced optical response with water, while the quasi-superhydrophobic state imparts the fragile antennas an ability to self-clean dust contamination. Furthermore, the metasurface can be easily switched and repeated between these two wettability or functional states by appropriate treatments in a repeatable way, without degrading the optical performance. The proposed design strategy will bring new opportunities to smart metasurfaces with improved optical performance, versatility, and physical stability.


Information extraction in photon-counting experiments

T. Schapeler, T. Bartley, Physical Review A (2022), 106(1), 013701

DOI


Laser-lithographically written micron-wide superconducting nanowire single-photon detectors

M. Protte, V.B. Verma, J.P. Höpker, R.P. Mirin, S. Woo Nam, T. Bartley, Superconductor Science and Technology (2022), 35(5), 055005

<jats:title>Abstract</jats:title> <jats:p>We demonstrate the fabrication of micron-wide tungsten silicide superconducting nanowire single-photon detectors on a silicon substrate using laser lithography. We show saturated internal detection efficiencies with wire widths ranging from 0.59 <jats:italic>µ</jats:italic>m to 1.43 <jats:italic>µ</jats:italic>m under illumination at 1550 nm. We demonstrate both straight wires, as well as meandered structures. Single-photon sensitivity is shown in devices up to 4 mm in length. Laser-lithographically written devices allow for fast and easy structuring of large areas while maintaining a saturated internal efficiency for wire widths around 1 <jats:italic>µ</jats:italic>m.</jats:p>


Cryogenic integrated spontaneous parametric down-conversion

N.A. Lange, J.P. Höpker, R. Ricken, V. Quiring, C. Eigner, C. Silberhorn, T. Bartley, Optica (2022), 9(1), 108

DOI


Cryogenic electro-optic modulation in titanium in-diffused lithium niobate waveguides

F. Thiele, F. vom Bruch, J. Brockmeier, M. Protte, T. Hummel, R. Ricken, V. Quiring, S. Lengeling, H. Herrmann, C. Eigner, C. Silberhorn, T. Bartley, Journal of Physics: Photonics (2022), 4(3), 034004

<jats:title>Abstract</jats:title> <jats:p>Lithium niobate is a promising platform for integrated quantum optics. In this platform, we aim to efficiently manipulate and detect quantum states by combining superconducting single photon detectors and modulators. The cryogenic operation of a superconducting single photon detector dictates the optimisation of the electro-optic modulators under the same operating conditions. To that end, we characterise a phase modulator, directional coupler, and polarisation converter at both ambient and cryogenic temperatures. The operation voltage <jats:inline-formula> <jats:tex-math><?CDATA $V_{\pi/2}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>V</mml:mi> <mml:mrow> <mml:mi>π</mml:mi> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpphotonac6c63ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> of these modulators increases, due to the decrease in the electro-optic effect, by 74% for the phase modulator, 84% for the directional coupler and 35% for the polarisation converter below 8.5<jats:inline-formula> <jats:tex-math><?CDATA $\,\mathrm{K}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">K</mml:mi> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpphotonac6c63ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. The phase modulator preserves its broadband nature and modulates light in the characterised wavelength range. The unbiased bar state of the directional coupler changed by a wavelength shift of 85<jats:inline-formula> <jats:tex-math><?CDATA $\,\mathrm{nm}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpphotonac6c63ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> while cooling the device down to 5<jats:inline-formula> <jats:tex-math><?CDATA $\,\mathrm{K}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">K</mml:mi> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpphotonac6c63ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>. The polarisation converter uses periodic poling to phasematch the two orthogonal polarisations. The phasematched wavelength of the utilised poling changes by 112<jats:inline-formula> <jats:tex-math><?CDATA $\,\mathrm{nm}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpphotonac6c63ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> when cooling to 5<jats:inline-formula> <jats:tex-math><?CDATA $\,\mathrm{K}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">K</mml:mi> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jpphotonac6c63ieqn6.gif" xlink:type="simple" /> </jats:inline-formula>.</jats:p>


Opto-electronic bias of a superconducting nanowire single photon detector using a cryogenic photodiode

F. Thiele, T. Hummel, M. Protte, T. Bartley, APL Photonics (2022), 7(8), 081303

<jats:p> Superconducting Nanowire Single Photon Detectors (SNSPDs) have become an integral part of quantum optics in recent years because of their high performance in single photon detection. We present a method to replace the electrical input by supplying the required bias current via the photocurrent of a photodiode situated on the cold stage of the cryostat. Light is guided to the bias photodiode through an optical fiber, which enables a lower thermal conduction and galvanic isolation between room temperature and the cold stage. We show that an off-the-shelf InGaAs–InP photodiode exhibits a responsivity of at least 0.55 A/W at 0.8 K. Using this device to bias an SNSPD, we characterize the count rate dependent on the optical power incident on the photodiode. This configuration of the SNSPD and photodiode shows an expected plateau in the single photon count rate with an optical bias power on the photodiode above 6.8 µW. Furthermore, we compare the same detector under both optical and electrical bias, and show there is no significant changes in performance. This has the advantage of avoiding an electrical input cable, which reduces the latent heat load by a factor of 100 and, in principle, allows for low loss RF current supply at the cold stage. </jats:p>


Two-Mode Photon-Number Correlations Created by Measurement-Induced Nonlinearity

T. Meier, J.P. Hoepker, M. Protte, C. Eigner, C. Silberhorn, P.R. Sharapova, J. Sperling, T. Bartley, in: Conference on Lasers and Electro-Optics: Applications and Technology, Optica Publishing Group, 2022, pp. JTu3A. 17

We demonstrate theoretically and experimentally complex correlations in the photon numbers of two-mode quantum states using measurement-induced nonlinearity. For this, we combine the interference of coherent states and single photons with photon sub-traction.


Electrochemical performance of KTiOAsO_4 (KTA) in potassium-ion batteries from density-functional theory

A. Bocchini, U. Gerstmann, T. Bartley, H. Steinrück, G. Henkel, W.G. Schmidt, Phys. Rev. Materials (2022), 6, pp. 105401


2021

Integrated superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides

J.P. Höpker, V.B. Verma, M. Protte, R. Ricken, V. Quiring, C. Eigner, L. Ebers, M. Hammer, J. Förstner, C. Silberhorn, R.P. Mirin, S. Woo Nam, T. Bartley, Journal of Physics: Photonics (2021), 3, pp. 034022

We demonstrate the integration of amorphous tungsten silicide superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides. We show proof-of-principle detection of evanescently coupled photons of 1550 nm wavelength using bidirectional waveguide coupling for two orthogonal polarization directions. We investigate the internal detection efficiency as well as detector absorption using coupling-independent characterization measurements. Furthermore, we describe strategies to improve the yield and efficiency of these devices.


Quantum detector tomography of a high dynamic-range superconducting nanowire single-photon detector

T. Schapeler, J.P. Höpker, T. Bartley, Superconductor Science and Technology (2021), 064002

DOI


Cryogenic Second-Harmonic Generation in Periodically Poled Lithium Niobate Waveguides

M. Bartnick, M. Santandrea, J.P. Höpker, F. Thiele, R. Ricken, V. Quiring, C. Eigner, H. Herrmann, C. Silberhorn, T. Bartley, Physical Review Applied (2021)

DOI


Generating two-mode squeezing with multimode measurement-induced nonlinearity

M. Riabinin, P. Sharapova, T. Bartley, T. Meier, Journal of Physics Communications (2021), 5(4)

DOI


2020

Cryogenic electro-optic polarisation conversion in titanium in-diffused lithium niobate waveguides

F. Thiele, F. vom Bruch, V. Quiring, R. Ricken, H. Herrmann, C. Eigner, C. Silberhorn, T. Bartley, Optics Express (2020), 28961

DOI


Towards Semiconductor-Superconductor-Crystal Hybrid Integration for Quantum Photonics

M. Protte, L. Ebers, M. Hammer, J.P. Höpker, M. Albert, V. Quiring, C. Meier, J. Förstner, C. Silberhorn, T. Bartley, in: OSA Quantum 2.0 Conference, 2020

We fabricate silicon tapers to increase the mode overlap of superconducting detectors on Ti:LiNbO3 waveguides. Mode images show a reduction in mode size from 6 µm to 2 µm FWHM, agreeing with beam propagation simulations.


Single-channel electronic readout of a multipixel superconducting nanowire single photon detector

J. Tiedau, T. Schapeler, V. Anant, H. Fedder, C. Silberhorn, T. Bartley, Optics Express (2020), 5528

DOI


Quantum detector tomography of a 2×2 multi-pixel array of superconducting nanowire single photon detectors

T. Schapeler, J.P. Höpker, T. Bartley, Optics Express (2020), 33035

DOI


Single-channel electronic readout of a multipixel superconducting nanowire single photon detector

J. Tiedau, T. Schapeler, V. Anant, H. Fedder, C. Silberhorn, T. Bartley, Optics Express (2020), 28(4), 5528

<jats:p>We present a time-over-threshold readout technique to count the number of activated pixels from an array of superconducting nanowire single photon detectors (SNSPDs). This technique places no additional heatload on the cryostat, and retains the intrinsic count rate of the time-tagger. We demonstrate proof-of-principle operation with respect to a four-pixel device. Furthermore, we show that, given some permissible error threshold, the number of pixels that can be reliably read out scales linearly with the intrinsic signal-to-noise ratio of the individual pixel response.</jats:p>


2019

Engineering integrated photon pair sources and multiplexed detectors (Conference Presentation)

E. Meyer-Scott, N. Prasannan, N. Montaut, J. Tiedau, C. Eigner, G. Harder, L. Sansoni, T. Nitsche, H. Herrmann, R. Ricken, V. Quiring, T. Bartley, S. Barkhofen, C. Silberhorn, in: Advances in Photonics of Quantum Computing, Memory, and Communication XII, 2019

DOI


A high dynamic range optical detector for measuring single photons and bright light

J. Tiedau, E. Meyer-Scott, T. Nitsche, S. Barkhofen, T. Bartley, C. Silberhorn, Optics Express (2019), 1

DOI


Scalability of parametric down-conversion for generating higher-order Fock states

J. Tiedau, T. Bartley, G. Harder, A.E. Lita, S.W. Nam, T. Gerrits, C. Silberhorn, Physical Review A (2019)

DOI


Integrated transition edge sensors on titanium in-diffused lithium niobate waveguides

J.P. Höpker, T. Gerrits, A. Lita, S. Krapick, H. Herrmann, R. Ricken, V. Quiring, R. Mirin, S.W. Nam, C. Silberhorn, T. Bartley, APL Photonics (2019), 056103

DOI



Generating two-mode squeezing with multimode measurement-induced nonlinearity

M. Riabinin, P. Sharapova, T. Bartley, T. Meier, in: arXiv:1912.09097, 2019

Measurement-induced nonclassical effects in a two-mode interferometer are investigated theoretically using numerical simulations and analytical results. We demonstrate that for certain parameters measurements within the interferometer lead to the occurrence of two-mode squeezing. The results strongly depend on the detection probability, the phase inside the interferometer, and the choice of the input states. The appropriate parameters for maximized squeezing are obtained. We analyze the influence of losses and confirm that the predicted effects are within reach of current experimental techniques.


2018

Engineering integrated sources of entangled photon pairs

E. Meyer-Scott, N. Prasannan, N. Montaut, J. Tiedau, G. Harder, L. Sansoni, H. Herrmann, C. Eigner, R. Ricken, V. Quiring, T. Bartley, S. Barkhofen, C. Silberhorn, in: Frontiers in Optics / Laser Science, 2018

DOI


Incomplete Detection of Nonclassical Phase-Space Distributions

M. Bohmann, J. Tiedau, T. Bartley, J. Sperling, C. Silberhorn, W. Vogel, Physical Review Letters (2018)

DOI


Heralded orthogonalisation of coherent states and their conversion to discrete-variable superpositions

R. Kruse, C. Silberhorn, T. Bartley, Quantum Measurements and Quantum Metrology (2018), 4(1)

<jats:title>Abstract</jats:title><jats:p>The nonorthogonality of coherent states is a fundamental property which prevents them from being perfectly and deterministically discriminated. Here, we present an experimentally feasible protocol for the probabilistic orthogonalisation of a pair of coherent states, independent of their amplitude and phase. In contrast to unambiguous state discrimination, a successful operation of our protocol is heralded without measuring the states. As such, they remain suitable for further manipulation and the obtained orthogonal states serve as a discretevariable basis. Therefore, our protocol doubles as a simple continuous-to-discrete variable converter, which may find application in hybrid continuous-discrete quantum information processing protocols.</jats:p>


Quantum state and mode profile tomography by the overlap

J. Tiedau, V.S. Shchesnovich, D. Mogilevtsev, V. Ansari, G. Harder, T. Bartley, N. Korolkova, C. Silberhorn, New Journal of Physics (2018), 033003

DOI


Compressive characterization of telecom photon pairs in the spatial and spectral degrees of freedom

N. Montaut, O.S. Magaña-Loaiza, T. Bartley, V.B. Verma, S.W. Nam, R.P. Mirin, C. Silberhorn, T. Gerrits, Optica (2018), 5(11), 1418

DOI


Incomplete Detection of Nonclassical Phase-Space Distributions

M. Bohmann, J. Tiedau, T. Bartley, J. Sperling, C. Silberhorn, W. Vogel, Physical Review Letters (2018)

DOI


2017

Full statistical mode reconstruction of a light field via a photon-number-resolved measurement

I.A. Burenkov, A.K. Sharma, T. Gerrits, G. Harder, T. Bartley, C. Silberhorn, E.A. Goldschmidt, S.V. Polyakov, Physical Review A (2017)

DOI


Limits on the heralding efficiencies and spectral purities of spectrally filtered single photons from photon-pair sources

E. Meyer-Scott, N. Montaut, J. Tiedau, L. Sansoni, H. Herrmann, T. Bartley, C. Silberhorn, Physical Review A (2017)

DOI


Discorrelated quantum states

E. Meyer-Scott, J. Tiedau, G. Harder, L.K. Shalm, T. Bartley, Scientific Reports (2017), 7

DOI


Limits of the time-multiplexed photon-counting method

R. Kruse, J. Tiedau, T. Bartley, S. Barkhofen, C. Silberhorn, Physical Review A (2017)

DOI


Driven Boson Sampling

S. Barkhofen, T. Bartley, L. Sansoni, R. Kruse, C.S. Hamilton, I. Jex, C. Silberhorn, Physical Review Letters (2017)

DOI


Harnessing temporal modes for multi-photon quantum information processing based on integrated optics

G. Harder, V. Ansari, T. Bartley, B. Brecht, C. Silberhorn, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences (2017), 375(2099), 20160244

<jats:p>In the last few decades, there has been much progress on low loss waveguides, very efficient photon-number detectors and nonlinear processes. Engineered sum-frequency conversion is now at a stage where it allows operation on arbitrary temporal broadband modes, thus making the spectral degree of freedom accessible for information coding. Hereby the information is often encoded into the temporal modes of a single photon. Here, we analyse the prospect of using multi-photon states or squeezed states in different temporal modes based on integrated optics devices. We describe an analogy between mode-selective sum-frequency conversion and a network of spatial beam splitters. Furthermore, we analyse the limits on the achievable squeezing in waveguides with current technology and the loss limits in the conversion process.</jats:p> <jats:p>This article is part of the themed issue ‘Quantum technology for the 21st century’.</jats:p>


Towards integrated superconducting detectors on lithium niobate waveguides

J.P. Höpker, M. Bartnick, E. Meyer-Scott, F. Thiele, T. Meier, T. Bartley, S. Krapick, N.M. Montaut, M. Santandrea, H. Herrmann, S. Lengeling, R. Ricken, V. Quiring, A.E. Lita, V.B. Verma, T. Gerrits, S.W. Nam, C. Silberhorn, in: Quantum Photonic Devices, SPIE, 2017, pp. 1035809

DOI


2016

Quantum Correlations from the Conditional Statistics of Incomplete Data

J. Sperling, T. Bartley, G. Donati, M. Barbieri, X. Jin, A. Datta, W. Vogel, I. Walmsley, Physical Review Letters (2016)

DOI


Quantum Correlations from the Conditional Statistics of Incomplete Data

J. Sperling, T. Bartley, G. Donati, M. Barbieri, X. Jin, A. Datta, W. Vogel, I. Walmsley, Physical Review Letters (2016)

DOI


Quantum enhanced estimation of optical detector efficiencies

M. Barbieri, A. Datta, T. Bartley, X. Jin, W.S. Kolthammer, I.A. Walmsley, Quantum Measurements and Quantum Metrology (2016)

<jats:title>Abstract</jats:title><jats:p>Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by identifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum channels involving the estimation of phase and loss parameters, we show that estimating the loss parameters associated with a quantum channel and a realistic quantum detector are fundamentally different. While Fock states are provably optimal for the former, we identify a crossover in the nature of the optimal probe state for estimating detector imperfections as a function of the loss parameter using Fisher information as a benchmark. We provide theoretical results for on-off and homodyne detectors, the most widely used detectors in quantum photonics technologies, when using Fock states and coherent states as probes.</jats:p>


Single-Mode Parametric-Down-Conversion States with 50 Photons as a Source for Mesoscopic Quantum Optics

G. Harder, T. Bartley, A.E. Lita, S.W. Nam, T. Gerrits, C. Silberhorn, Physical Review Letters (2016)

DOI


2015

Directly comparing entanglement-enhancing non-Gaussian operations

T. Bartley, I.A. Walmsley, New Journal of Physics (2015), 023038

DOI


2014

Observing optical coherence across Fock layers with weak-field homodyne detectors

G. Donati, T. Bartley, X. Jin, M. Vidrighin, A. Datta, M. Barbieri, I.A. Walmsley, Nature Communications (2014)

DOI


2013

Direct Observation of Sub-Binomial Light

T. Bartley, G. Donati, X. Jin, A. Datta, M. Barbieri, I.A. Walmsley, Physical Review Letters (2013)

DOI


Strategies for enhancing quantum entanglement by local photon subtraction

T. Bartley, P.J.D. Crowley, A. Datta, J. Nunn, L. Zhang, I. Walmsley, Physical Review A (2013)

DOI


Requirements for two-source entanglement concentration

M. Vidrighin, T. Bartley, G. Donati, X. Jin, M. Barbieri, W.S. Kolthammer, A. Datta, I.A. Walmsley, Quantum Measurements and Quantum Metrology (2013)

DOI


2012

Multiphoton state engineering by heralded interference between single photons and coherent states

T. Bartley, G. Donati, J.B. Spring, X. Jin, M. Barbieri, A. Datta, B.J. Smith, I.A. Walmsley, Physical Review A (2012)

DOI


2011

Continuous phase stabilization and active interferometer control using two modes

G. Jotzu, T. Bartley, H.B. Coldenstrodt-Ronge, B.J. Smith, I.A. Walmsley, Journal of Modern Optics (2011), pp. 42-45

DOI


2009

Atmospheric channel characteristics for quantum communication with continuous polarization variables

B. Heim, D. Elser, T. Bartley, M. Sabuncu, C. Wittmann, D. Sych, C. Marquardt, G. Leuchs, Applied Physics B (2009), pp. 635-640

DOI


Feasibility of free space quantum key distribution with coherent polarization states

D. Elser, T. Bartley, B. Heim, C. Wittmann, D. Sych, G. Leuchs, New Journal of Physics (2009)(4), pp. 045014

We demonstrate for the first time the feasibility of free space quantum key distribution with continuous variables under real atmospheric conditions. More specifically, we transmit coherent polarization states over a 100 m free space channel on the roof of our institute's building. In our scheme, signal and local oscillator (LO) are combined in a single spatial mode, which auto-compensates atmospheric fluctuations and results in an excellent interference. Furthermore, the LO acts as a spatial and spectral filter, thus allowing unrestrained daylight operation.


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