arXiv subjects

Nicolas Treps

Publications and source records attributed to Nicolas Treps.

At least 109 records · Page 6Linked to original sources

arXiv2012

A time/frequency quantum analysis of the light generated by synchronously pumped optical parametric oscillators

We present in this paper a general model for determining the quantum properties of the light generated by a synchronously pumped optical parametric oscillator (SPOPO) operating below threshold. This model considers time and frequency on an equal footing, which allows us to find new quantum properties, related for example to the carrier envelope offset (CEO) phase, and to consider situations that are close to real experiments. We show that, in addition to multimode squeezing in the so-called 'supermodes', the system exhibits quadrature entanglement between frequency combs of opposite CEO phases. We have also determined the quantum properties of the individual pulses and their quantum correlations with the neighboring pulses. Finally, we determine the quantum Cramer-Rao limit for an ultra-short time delay measurement using a given number of pulses generated by the SPOPO.

quant-ph↗

arXiv2011

Generation and characterization of multimode quantum frequency combs

Multimode nonclassical states of light are an essential resource in quantum computation with continuous variables, for example in cluster state computation. They can be generated either by mixing different squeezed light sources using linear optical operations, or directly in a multimode optical device. In parallel, frequency combs are perfect tools for high precision metrological applications and for quantum time transfer. Synchronously Pumped Optical Parametric Oscillators (SPOPOs) have been theoretically shown to produce multimode non-classical frequency combs. In this paper, we present the first experimental generation and characterization of a femtosecond quantum frequency comb generated by a SPOPO. In particular, we give the experimental evidence of the multimode nature of the generated quantum state and, by studying the spectral noise distribution of this state, we show that at least three nonclassical independent modes are required to describe it.

quant-ph↗

arXiv2011

Ultimate sensitivity of precision measurements with Gaussian quantum light : a multi-modal approach

Multimode Gaussian quantum light, which includes multimode squeezed and multipartite quadrature entangled light, is a very general and powerful quantum resource with promising applications in quantum information processing and metrology. In this paper, we determine the ultimate sensitivity in the estimation of any parameter when the information about this parameter is encoded in such light, irrespective of the information extraction protocol used in the estimation and of the measured observable. In addition we show that an appropriate homodyne detection scheme allows us to reach this ultimate sensitivity. We show that, for a given set of available quantum resources, the most economical way to maximize the sensitivity is to put the most squeezed state available in a well-de ned light mode. This implies that it is not possible to take advantage of the existence of squeezed fluctuations in other modes, nor of quantum correlations and entanglement between diff erent modes.

quant-ph↗

arXiv2011

Quantum correlated pulses from a synchronously pumped optical parametric oscillator operating above threshold

We perform the quantum analysis of the light emitted by a synchronously pumped optical parametric oscillator operating in the above threshold regime, i.e. when the peak power of pulsed pumping exceeds the threshold of continuous generation. We show that both regimes (below and above threshold) are realized at different times within each pulse of the signal field. We show that the quantum fluctuations of signal and pump pulses are correlated between nearby pulses at times that are placed in the same position relative to the center of the pulses, whereas fluctuations are totally not correlated at different times within the same pulse. The model also predicts the existence of cross-correlations between pump and signal pulses. It is shown theoretically that there is suppression of quantum noise at the frequencies multiple of the pulse repetition frequency in the spectra of phase quadratures of pump and signal fields measured by a balanced homodyne detection with a pulsed local oscillator.

quant-ph↗

arXiv2011

Direct generation of a multi-transverse mode non-classical state of light

Quantum computation and communication protocols require quantum resources which are in the continuous variable regime squeezed and/or quadrature entangled optical modes. To perform more and more complex and robust protocols, one needs sources that can produce in a controlled way highly multimode quantum states of light. One possibility is to mix different single mode quantum resources. Another is to directly use a multimode device, either in the spatial or in the frequency domain. We present here the first experimental demonstration of a device capable of producing simultanuously several squeezed transverse modes of the same frequency and which is potentially scalable. We show that this device, which is an Optical Parametric Oscillator using a self-imaging cavity, produces a multimode quantum resource made of three squeezed transverse modes.

quant-ph↗

arXiv2010

General Cramér-Rao bound for parameter estimation using Gaussian multimode quantum resources

Multimode Gaussian quantum light, including multimode squeezed and/or multipartite quadrature entangled light, is a very general and powerful quantum resource with promising applications to quantum information processing and metrology involving continuous variables. In this paper, we determine the ultimate sensitivity in the estimation of any parameter when the information about this parameter is encoded in such Gaussian light, irrespective of the exact information extraction protocol used in the estimation. We then show that, for a given set of available quantum resources, the most economical way to maximize the sensitivity is to put the most squeezed state available in a well-defined light mode. This implies that it is not possible to take advantage of the existence of squeezed fluctuations in other modes, nor of quantum correlations and entanglement between different modes. We show that an appropriate homodyne detection scheme allows us to reach this Cramr-Rao bound. We apply finally these considerations to the problem of optimal phase estimation using interferometric techniques.

quant-ph↗

arXiv2010

Programmable unitary spatial modes manipulation

Free space propagation and conventional optical systems such as lenses and mirrors all perform spatial unitary transforms. However, the subset of transforms available through these conventional systems is limited in scope. We present here a unitary programmable mode converter (UPMC) capable of performing any spatial unitary transform of the light field. It is based on a succession of reflections on programmable deformable mirrors and free space propagation. We first show theoretically that a UPMC without limitations on resources can perform perfectly any transform. We then build an experimental implementation of the UPMC and show that, even when limited to three reflections on an array of 12 pixels, the UPMC is capable of performing single mode tranforms with an efficiency greater than 80% for the first 4 modes of the TEM basis.

physics.optics↗

arXiv2009

Multimode non-classical light generation through the OPO threshold

We show that an Optical Parametric Oscillator which is simultaneously resonant for several modes, either spatial or temporal, generates both below and above threshold a multimode non-classical state of light consisting of squeezed vacuum states in all the non-oscillating modes. We confirm this prediction by an experiment dealing with the degenerate TEM$_{01}$ and TEM$_{10}$ modes. We show the conservation of non-classical properties when the threshold is crossed. The experiment is made possible by the implementation of a new method to lock the relative phase of the pump and the injected beam.

quant-ph↗

arXiv2009

Quantum theory of Synchronously Pumped type I Optical Parametric Oscillators: characterization of the squeezed supermodes

Quantum models for synchronously pumped type I optical parametric oscillators (SPOPO) are presented. The study of the dynamics of SPOPOs, which typically involves millions of coupled signal longitudinal modes, is significantly simplified when one considers the ?supermodes?, which are independent linear superpositions of all the signal modes diagonalizing the parametric interaction. In terms of these supermodes the SPOPO dynamics becomes that of about a hundred of independent, single mode degenerate OPOs, each of them being a squeezer. One derives a general expression for the squeezing spectrum measured in a balanced homodyne detection experiment, valid for any temporal shape of the local oscillator. Realistic cases are then studied using both analytical and numerical methods: the oscillation threshold is derived, and the spectral and temporal shapes of the squeezed supermodes are characterized.

quant-ph↗

arXiv2008

Multimode quantum properties of a self-imaging OPO: squeezed vacuum and EPR beams generation

We investigate the spatial quantum properties of the light emitted by a perfectly spatially degenerate optical parametric oscillator (self-imaging OPO). We show that this device produces local squeezing for areas bigger than a coherence are that depends on the crystal length and pump width. Furthermore, it generates local EPR beams in the far field. We show, calculating the eigenmodes of the system, that it is highly multimode for realistic experimental parameters.

quant-ph↗

arXiv2008

Experimental demonstration of frequency-degenerate bright EPR beams with a self-phase-locked optical parametric oscillator

We report the first experimental observation of bright EPR beams produced by a type-II optical parametric oscillator operating above threshold at frequency degeneracy. The degenerate operation is obtained by introducing a birefringent plate inside the cavity resulting in phase locking. After filtering the pump noise, which plays a critical role, continuous-variable EPR correlations between the orthogonally polarized signal and idler beams are demonstrated.

quant-ph↗

arXiv2008

Quantum improvement of time transfer between remote clocks

Exchanging light pulses to perform accurate space-time positioning is a paradigmatic issue of physics. It is ultimately limited by the quantum nature of light, which introduces fluctuations in the optical measurements and leads to the so-called Standard Quantum Limit (SQL). We propose a new scheme combining homodyne detection and mode-locked femtosecond lasers that lead to a new SQL in time transfer, potentially reaching the yoctosecond range (10^-21-10^-24 s). We prove that no other measurement strategy can lead to better sensitivity with shot noise limited light. We then demonstrate that this already very low SQL can be overcome using appropriately multimode squeezed light. Benefitting from the large number of photons used in the experiment and from the optimal choice of both the detection strategy and of the quantum resource, the proposed scheme represents a significant potential improvement in space-time positioning.

quant-ph↗

arXiv2007

Quantum state of an injected TROPO above threshold : purity, Glauber function and photon number distribution

In this paper we investigate several properties of the full signal-idler-pump mode quantum state generated by a triply resonant non-degenerate Optical Parametric Oscillator operating above threshold, with an injected wave on the signal and idler modes in order to lock the phase diffusion process. We determine and discuss the spectral purity of this state, which turns out not to be always equal to 1 even though the three interacting modes have been taken into account at the quantum level. We have seen that the purity is essentially dependent on the weak intensity of the injected light and on an asymmetry of the synchronization. We then derive the expression of its total three-mode Glauber P-function, and calculate the joint signal-idler photon number probability distribution and investigate their dependence on the injection.

quant-ph↗

arXiv2006

Quantum limits in image processing

We determine the bound to the maximum achievable sensitivity in the estimation of a scalar parameter from the information contained in an optical image in the presence of quantum noise. This limit, based on the Cramer-Rao bound, is valid for any image processing protocol. It is calculated both in the case of a shot noise limited image and of a non-classical illumination. We also give practical experimental implementations allowing us to reach this absolute limit.

quant-ph↗

arXiv2006

TEM10 homodyne detection as an optimal small displacement and tilt measurements scheme

We report an experimental demonstration of optimal measurements of small displacement and tilt of a Gaussian beam - two conjugate variables - involving a homodyne detection with a TEM10 local oscillator. We verify that the standard split detection is only 64% efficient. We also show a displacement measurement beyond the quantum noise limit, using a squeezed vacuum TEM10 mode within the input beam.

quant-ph↗

arXiv2006

Generation of Squeezing in Higher Order Hermite-Gaussian Modes with an Optical Parametric Amplifier

We demonstrate quantum correlations in the transverse plane of continuous wave light beams by producing -4.0 dB, -2.6 dB and -1.5 dB of squeezing in the TEM00, TEM10 and TEM20 Hermite- Gauss modes with an optical parametric amplifier, respectively. This has potential applications in quantum information networking, enabling parallel quantum information processing. We describe the setup for the generation of squeezing and analyze the effects of various experimental issues such as mode overlap between pump and seed and nonlinear losses.

quant-ph↗

arXiv2006

Squeezing frequency combs

We have developed the full theory of a synchronously pumped type I optical parametric oscillator (SPOPO). We derive expressions for the oscillation threshold and the characteristics of the generated mode-locked signal beam. We calculate the output quantum fluctuations of the device, and find that, in the degenerate case (coincident signal and idler set of frequencies), perfect squeezing is obtained when one approaches threshold from below for a well defined "super-mode', or frequency comb, consisting of a coherent linear superposition of signal modes of different frequencies which are resonant in the cavity.

quant-ph↗

arXiv2005

Optical storage of high density information beyond the diffraction limit : a quantum study

We propose an optical read-out scheme allowing a demonstration of principle of information extraction below the diffraction limit. This technique, which could lead to improvement in data read-out density onto optical discs, is independent from the wavelength and numerical aperture of the reading apparatus, and involves a multi-pixel array detector. Furthermore, we show how to use non classical light in order to perform bit discrimination beyond the quantum noise limit.

quant-ph↗