Witnessing effective entanglement over a 2km fiber channel (2009)
Wittmann, Christoffer, Fürst, Josef, Wiechers, Carlos, Elser, Dominique, Häseler, Hauke, Lütkenhaus, Norbert, ...
We present a fiber-based continuous-variable quantum key distribution system. In the scheme, a quantum signal of two non-orthogonal weak optical coherent states is sent through a fiber-based quantum...
Two-Color Bright Squeezed Vacuum (2009)
Agafonov, Ivan N., Chekhova, Maria V., Leuchs, Gerd
In a strongly pumped non-degenerate type-I traveling-wave OPA, we produce two-color squeezed vacuum with photon numbers as high as hundreds of photons per mode, or millions of photons per pulse. By...
Heim, Bettina, Elser, Dominique, Bartley, Tim, Sabuncu, Metin, Wittmann, Christoffer, Sych, Denis, ...
We investigate the properties of an atmospheric channel for free space quantum communication with continuous polarization variables. In our prepare-and-measure setup, coherent polarization states are...
Enhanced free space beam capture by improved optical tapers (2009)
Bartley, Tim, Heim, Bettina, Elser, Dominique, Sych, Denis, Sabuncu, Metin, Wittmann, Christoffer, ...
In our continuous variable quantum key distribution (QKD) scheme, the homodyne detection set-up requires balancing the intensity of an incident beam between two photodiodes. Realistic lens systems...
Environmental Assisted Quantum Information Correction for Continuous Variables (2009)
Sabuncu, Metin, Filip, Radim, Leuchs, Gerd, Andersen, Ulrik L.
Quantum information protocols are inevitably affected by decoherence which is associated with the leakage of quantum information into an environment. In this paper we address the possibility of...
Demonstration of a Photon Number Resolving Receiver for Optical Coherent States (2009)
Wittmann, Christoffer, Andersen, Ulrik L., Leuchs, Gerd
We investigate quantum measurement strategies capable of discriminating two coherent states probabilistically with significantly smaller error probabilities than can be obtained using...
Triplet-like correlation symmetry of continuous variable entangled states (2009)
Leuchs, Gerd, Dong, Ruifang, Sych, Denis
We report on a continuous variable analogue of the triplet two-qubit Bell states. We theoretically and experimentally demonstrate a remarkable similarity of two-mode continuous variable entangled...
Discrimination of Optical Coherent States using a Photon Number Resolving Detector (2009)
Wittmann, Christoffer, Andersen, Ulrik L., Leuchs, Gerd
The discrimination of non-orthogonal quantum states with reduced or without errors is a fundamental task in quantum measurement theory. In this work, we investigate a quantum measurement strategy...
Correlation Measurement of Squeezed Light (2009)
Krivitsky, Leonid A., Andersen, Ulrik L., Dong, Ruifang, Huck, Alexander, Wittmann, Christoffer, Leuchs, Gerd
We study the implementation of a correlation measurement technique for the characterization of squeezed light which is nearly free of electronic noise. With two different sources of squeezed light,...
A Novel Method for Polarization Squeezing with Photonic Crystal Fibers (2009)
Milanovic, Josip, Lassen, Mikael, Andersen, Ulrik L., Leuchs, Gerd
Photonic Crystal Fibers can be tailored to increase the nonlinear Kerr effect while producing small amounts of excess noise. Using these features we create polarization squeezed states with higher...
Geometric Spin Hall Effect of Light (2009)
Aiello, Andrea, Marquardt, Christoph, Leuchs, Gerd
We describe a novel phenomenon occurring when a polarized Gaussian beam of light is observed in a Cartesian reference frame whose axes are not parallel to the direction of propagation of the beam....
Coherent State Quantum Key Distribution with Multi Letter Alphabets (2009)
We present a protocol for continuous-variable quantum key distribution. The novelty of the protocol is an optimized multi letter alphabet composed of coherent states of light with fixed amplitude and...
Continuous Variable Entanglement and Squeezing of Orbital Angular Momentum States (2009)
Lassen, Mikael, Leuchs, Gerd, Andersen, Ulrik L.
We report the first experimental characterization of the first-order continuous variable orbital angular momentum states. Using a spatially non-degenerate optical parametric oscillator (OPO) we...
Experimental entanglement distillation of mesoscopic quantum states (2008)
Dong, Ruifang, Lassen, Mikael, Heersink, Joel, Marquardt, Christoph, Filip, Radim, Leuchs, Gerd, ...
The distribution of entangled states between distant parties in an optical network is crucial for the successful implementation of various quantum communication protocols such as quantum...
Maximizing the electric field strength in the foci of high numerical aperture optics (2008)
Sondermann, Markus, Lindlein, Norbert, Leuchs, Gerd
Several applications require spatial distributions of the incident electric field that maximize the electric field at a focal point for a given input power. The field distributions are derived for...
Ion traps with enhanced optical and physical access (2008)
Maiwald, Robert, Leibfried, Dietrich, Britton, Joe, Bergquist, J. C., Leuchs, Gerd, Wineland, D. J.
Small, controllable, highly accessible quantum systems can serve as probes at the single quantum level to study multiple physical effects, for example in quantum optics or for electric and magnetic...
Two-Photon Polarization Interference for Pulsed SPDC in a PPKTP Waveguide (2008)
Avenhaus, Malte, Chekhova, Maria V., Krivitsky, Leonid A., Leuchs, Gerd, Silberhorn, Christine
We study the spectral properties of Spontaneous Parametric Down Conversion in a periodically poled waveguided structure of KTP crystal pumped by ultra-short pulses. Our theoretical analysis reveals a...
Perfect excitation of a matter qubit by a single photon in free space (2008)
Stobińska, Magdalena, Alber, Gernot, Leuchs, Gerd
We propose a scheme for perfect excitation of a single two-level atom by a single photon in free space. The photon state has to match the time reversed photon state originating from spontaneous decay...
Simulations and Experiments on Polarisation Squeezing in Optical Fibre (2008)
Corney, Joel F., Heersink, Joel, Dong, Ruifang, Josse, Vincent, Drummond, Peter D., Leuchs, Gerd, ...
We investigate polarisation squeezing of ultrashort pulses in optical fibre, over a wide range of input energies and fibre lengths. Comparisons are made between experimental data and quantum...
Electronic noise-free measurements of squeezed light (2008)
Krivitsky, Leonid A., Andersen, Ulrik L., Dong, Ruifang, Huck, Alexander, Wittmann, Christoffer, Leuchs, Gerd
We study the implementation of a correlation measurement technique for the characterization of squeezed light. We show that the sign of the covariance coefficient revealed from the time resolved...
Experimental continuous variable cloning of partial quantum information (2008)
Sabuncu, Metin, Leuchs, Gerd, Andersen, Ulrik L.
The fidelity of a quantum transformation is strongly linked with the prior partial information of the state to be transformed. We illustrate this interesting point by proposing and demonstrating the...
Simulations and experiments on polarization squeezing in optical fibre (2008)
Corney, Joel F., Heersink, Joel, Dong, Ruifang, Josse, Vincent, Drummond, Peter D., Leuchs, Gerd, ...
We investigate polarization squeezing of ultrashort pulses in optical fibre, over a wide range of input energies and fibre lengths. Comparisons are made between experimental data and quantum...
Experimental evidence for Raman-induced limits to efficient squeezing in optical fibers (2008)
Dong, Ruifang, Heersink, Joel, Corney, Joel F., Drummond, Peter D., Andersen, Ulrik L., Leuchs, Gerd
We report new experiments on polarization squeezing using ultrashort photonic pulses in a single pass of a birefringent fibre. We measure what is to our knowledge a record squeezing of -6.8±0.3...
Simulations and experiments on polarization squeezing in optical fiber (2008)
Corney, Joel F., Heersink, Joel, Dong, Ruifang, Josse, Vincent, Drummond, Peter D., Leuchs, Gerd, ...
We investigate polarization squeezing of ultrashort pulses in optical fiber, over a wide range of input energies and fiber lengths. Comparisons are made between experimental data and quantum...
Simulations and experiments on polarization squeezing in optical fibre (2008)
Corney, Joel F., Heersink, Joel, Dong, Ruifang, Josse, Vincent, Drummond, P. D., Leuchs, Gerd, ...
We investigate polarization squeezing of ultrashort pulses in optical fibre, over a wide range of input energies and fibre lengths. Comparisons are made between experimental data and quantum...
Experimental evidence for Raman-induced limits to efficient squeezing in optical fibers (2008)
Dong, Ruifang, Heersink, Joel, Corney, Joel F., Drummond, P. D., Andersen, Ulrik L., Leuchs, Gerd
We report new experiments on polarization squeezing using ultrashort photonic pulses in a single pass of a birefringent fibre. We measure what is to our knowledge a record squeezing of -6.8±0.3 dB...
An efficient source of continuous variable polarisation entanglement (2007)
Dong, Ruifang, Heersink, Joel, Yoshikawa, Jun-ichi, Gloeckl, Oliver, Andersen, Ulrik L., Leuchs, Gerd
We have experimentally demonstrated the efficient creation of highly entangled bipartite continuous variable polarisation states. Exploiting an optimised scheme for the production of squeezing using...
Raman-induced limits to efficient squeezing in optical fibers (2007)
Dong, Ruifang, Heersink, Joel, Corney, Joel F., Drummond, Peter D., Andersen, Ulrik L., Leuchs, Gerd
We report new experiments on polarization squeezing using ultrashort photonic pulses in a single pass of a birefringent fiber. We measure what is to our knowledge a record squeezing of -6.8 +/- 0.3...
Non-unity gain minimal disturbance measurement (2007)
Sabuncu, Metin, Mišta, Ladislav, Fiurášek, Jaromír, Filip, Radim, Leuchs, Gerd, ...
We propose and experimentally demonstrate an optimal non-unity gain Gaussian scheme for partial measurement of an unknown coherent state that causes minimal disturbance of the state. The information...
Experimental Demonstration of Macroscopic Quantum Coherence in Gaussian States (2007)
Marquardt, Christoph, Andersen, Ulrik L., Leuchs, Gerd, Takeno, Yuishi, Yukawa, Mitsuyoshi, Yonezawa, Hidehiro, ...
We witness experimentally the presence of macroscopic coherence in Gaussian quantum states using a recently proposed criterion (E.G. Cavalcanti and M. Reid, Phys. Rev. Lett. 97, 170405 (2006)). The...
Quantum Limits To Center-of-mass Measurements (2007)
Vaughan, Timothy., Drummond, Peter D., Leuchs, Gerd
We discuss the issue of measuring the mean position (center of mass) of a group of bosonic or fermionic quantum particles, including particle number fluctuations. We introduce a standard quantum...
Quantum Limits To Center-of-mass Measurements (2007)
Vaughan, Timothy., Drummond, Peter D., Leuchs, Gerd
We discuss the issue of measuring the mean position (center of mass) of a group of bosonic or fermionic quantum particles, including particle number fluctuations. We introduce a standard quantum...
Quantum limits to center-of-mass measurements (2007)
Vaughan, Timothy, Drummond, Peter, Leuchs, Gerd
We discuss the issue of measuring the mean position (center of mass) of a group of bosonic or fermionic quantum particles, including particle number fluctuations. We introduce a standard quantum...
Quantum limits to center-of-mass measurements (2007)
Vaughan, Timothy, Drummond, P. D., Leuchs, Gerd
We discuss the issue of measuring the mean position (center of mass) of a group of bosonic or fermionic quantum particles, including particle number fluctuations. We introduce a standard quantum...
Experimental Demonstration of Continuous Variable Cloning with Phase-Conjugate Inputs (2006)
Sabuncu, Metin, Andersen, Ulrik L., Leuchs, Gerd
We report the experimental demonstration of continuous variable cloning of phase conjugate coherent states as proposed by Cerf and Iblisdir (Phys. Rev. Lett. 87, 247903 (2001)). In contrast to the...
Quantum limits to center-of-mass measurements (2006)
Vaughan, Timothy, Drummond, Peter, Leuchs, Gerd
We discuss the issue of measuring the mean position (center-of-mass) of a group of bosonic or fermionic quantum particles, including particle number fluctuations. We introduce a standard quantum...
Many-body quantum dynamics of polarization squeezing in optical fibers (2006)
Corney, Joel F., Drummond, Peter D., Heersink, Joel, Josse, Vincent, Leuchs, Gerd, Andersen, Ulrik L.
We report new experiments that test quantum dynamical predictions of polarization squeezing for ultrashort photonic pulses in a birefringent fiber, including all relevant dissipative effects. This...
Many-body quantum dynamics of polarization squeezing in optical fibers (2006)
Corney, Joel F., Drummond, Peter D., Heersink, Joel, Josse, Vincent, Leuchs, Gerd, Andersen, Ulrik L.
We report new experiments that test quantum dynamical predictions of polarization squeezing for ultrashort photonic pulses in a birefringent fibre, including all relevant dissipative effects. This...
Quantum simulations of a fibre squeezing experiment (2006)
Heersink, Joel, Corney, Joel, Josse, Vincent, Leuchs, Gerd, Drummond, Peter D., Andersen, Ulrik L.
We report on the excellent agreement of a first-principles, quantum dynamical simulation with the experimentally measured results of a fibre squeezer using intense, ultra-short laser pulses.
Many-body quantum dynamics of polarization squeezing in optical fibers (2006)
Corney, Joel F., Drummond, P. D., Heersink, Joel, Josse, Vincent, Leuchs, Gerd, Andersen, Ulrik L.
We report new experiments that test quantum dynamical predictions of polarization squeezing for ultrashort photonic pulses in a birefringent fibre, including all relevant dissipative effects. This...
Quantum simulations of a fibre squeezing experiment (2006)
Heersink, Joel, Corney, Joel, Josse, Vincent, Leuchs, Gerd, Drummond, P. D., Andersen, Ulrik L.
We report on the excellent agreement of a first-principles, quantum dynamical simulation with the experimentally measured results of a fibre squeezer using intense, ultra-short laser pulses.
Experimental demonstration of coherent state estimation with minimal disturbance (2005)
Andersen, Ulrik L., Sabuncu, Metin, Filip, Radim, Leuchs, Gerd
We investigate the optimal tradeoff between information gained about an unknown coherent state and the state disturbance caused by the measurement process. We propose several optical schemes that can...
Experimental purification of coherent states (2005)
Andersen, Ulrik L., Filip, Radim, Fiurasek, Jaromir, Josse, Vincent, Leuchs, Gerd
We propose a scheme for optimal Gaussian purification of coherent states from several imperfect copies. The proposal is experimentally demonstrated for the case of two copies of a coherent state sent...
Unconditional quantum cloning of coherent states with linear optics (2005)
Andersen, Ulrik L., Josse, Vincent, Leuchs, Gerd
A scheme for optimal Gaussian cloning of optical coherent states is proposed and experimentally demonstrated. Its optical realization is based entirely on simple linear optical elements and homodyne...
Experimental demonstration of continuous variable quantum erasing (2004)
Andersen, Ulrik L., Glöckl, Oliver, Lorenz, Stefan, Leuchs, Gerd, Filip, Radim
We experimentally demonstrate the concept of continuous variable quantum erasing. The amplitude quadrature of the signal state is labelled to another state via a quantum nondemolition interaction,...
All-fibre source of amplitude-squeezed light pulses (2004)
Meissner, Markus, Marquardt, Christoph, Heersink, Joel, Gaber, Tobias, Wietfeld, André, Leuchs, Gerd, ...
An all-fibre source of amplitude squeezed solitons utilizing the self-phase modulation in an asymmetric Sagnac interferometer is experimentally demonstrated. The asymmetry of the interferometer is...
Continuous variable quantum key distribution using polarization encoding and post selection (2004)
Lorenz, Stefan, Korolkova, Natalia, Leuchs, Gerd
We present an experimental demonstration of a quantum key distribution protocol using coherent polarization states. Post selection is used to ensure a low error rate and security against beam...
The focus of light - linear polarization breaks the rotational symmetry of the focal spot (2003)
Dorn, Ralf, Quabis, Susanne, Leuchs, Gerd
We experimentally demonstrate for the first time that a linearly polarized beam is focussed to an asymmetric spot when using a high-numerical aperture focussing system. This asymmetry was predicted...
Glöckl, Oliver, Lorenz, Stefan, Marquardt, Christoph, Heersink, Joel, Brownnutt, Michel, Silberhorn, Christine, ...
We present a protocol for performing entanglement swapping with intense pulsed beams. In a first step, the generation of amplitude correlations between two systems that have never interacted directly...
Polarization squeezing and continuous-variable polarization entanglement (2001)
Korolkova, Natalia, Leuchs, Gerd, Loudon, Rodney, Ralph, Timothy C., Silberhorn, Christine
The Stokes-parameter operators and the associated Poincare sphere, which describe the quantum-optical polarization properties of light, are defined and their basic properties are reviewed. The...
Time evolution of a quantum soliton in a Kerr medium (2001)
Korolkova, Natalia, Loudon, Rodney, Gardavsky, Gerlinde, Hamilton, Murray Wayne, Leuchs, Gerd
The Q-function of the quantum soliton in a fibre is derived in a new form suitable for the assessment of the possibilities for experimental observations of specific quantum-soliton effects. The...
Time evolution of a quantum soliton in a Kerr medium (2001)
Korolkova, Natalia, Loudon, Rodney, Gardavsky, Gerlinde, Hamilton, Murray Wayne, Leuchs, Gerd
The Q-function of the quantum soliton in a fibre is derived in a new form suitable for the assessment of the possibilities for experimental observations of specific quantum-soliton effects. The...