Charge sensing amplification via weak values measurement

A protocol employing weak values (WVs) to obtain ultrasensitive amplification of weak signals in the context of a solid-state setup is proposed. We consider an Aharonov-Bohm interferometer where both the orbital and the spin degrees of freedom are weakly affected by the presence of an external charge to be detected. The interplay between the spin and the orbital WVs leads to a significant amplification even in the presence of finite temperature, voltage, and external noise.     

Large polarization squeezing in non-degenerate parametric amplification of coherent radiation

Polarization squeezing is shown to occur in non-degenerate parametric amplification of coherent light and the degree of squeezing at interaction time T can be as large as 1 ? e^-2T. This gives 86.4% polarization squeezing for T = 1 and 98.2% for T = 2. One simple case when this occurs is on taking initially plane polarized light having equal amplitudes in the two modes that finally has equal intensities of two circular polarizations. This suggest the experimental settings of parameters to achieve this extent of polarization squeezing in coherent light.     

Light squeezing in optical parametric amplification beyond the slowly-varying amplitude approximation

Optical parametric amplification (OPA) described usually by the coupled-wave equations with the first-order derivatives of the signal and idler waves, is solved under the slowly-varying amplitude approximation (SVA). In this article, by keeping the second-order derivatives in the coupled-wave equations, we obtained an analytical solution for the output signal and idler waves up to the first order of (κ/k)¹; the ratio of coupling constant to the wave number. Furthermore, here the signal and the idler waves are distinguished only by their polarizations with the same frequency. Light squeezing is observed in normally ordered variances of the two quadrature operators of the output combined mode when plotted against κL, where κ is the coupling constant and L the interaction length. The variances have different signs for a range of values of κL and their variations are in opposite directions. We also show that this property is strongly dependent on the relative refractive index of the medium (n). It is worth mentioning that the relative index dependency is not an explicit feature in squeezing of OPA under SVA approximation. Furthermore, the squeezing vanishes when n → 1 and κ/k → 0.     

3 dB squeezing by single-pass parametric amplification in a periodically poled KTiOPO4 crystal

We present the experimental observation of pulsed squeezed light from a degenerate optical parametric amplifier pumped by a second harmonic of a continuous-wave mode-locked Nd:YVO4 laser. With a single pass through a 10 mm long periodically poled KTiOPO4 crystal, the classical parametric gain of 11 is observed. The measured noise reduction in the quiet quadrature is 3.2 dB below the shot-noise level.     

Generation of spin squeezing via continuous quantum nondemolition measurement

Continuous quantum nondemolition monitoring of a collective atomic spin with an off-resonant laser beam has been performed. Squeezed atomic spin states have thereby been produced with spin noise reduction to 70% below the standard quantum limit expected for a coherent spin state.     

Ultrasmall polarization rotation measurements via weak value amplification

We propose a framework to analyze weak measurements based on an angular version of the von Neumann measurement scheme, where the coupling between the system and the meter causes rotation of the measuring variable. We also discuss an experimental application of this theory in which measurements of weak optical activity and reflection-induced polarization rotation could be amplified in nearly two orders of magnitude. It can shed a new light on a great variety of physical chemistry, molecular biology and nanotechnology studies.     

Large temporal window contrast measurement using optical parametric amplification and low-sensitivity detectors

To address few-shot pulse contrast measurement, we present a correlator coupling the high gain of an optical parametric amplification scheme with large pulse tilt. This combination enables a low sensitivity charge coupled device (CCD) to observe features in the pulse intensity within a 50 ps single-shot window with inter-window dynamic range >10⁷ and <0.5 mJ input energy. We also consider use of optical densities to boost the CCD dynamic range within a single temporal window.     

Non-classical effect of quantum non-demolition measurement in presence of parametric amplification

A full quantum treatment of the problem of quantum non-demolition measurements in non-linear optical media is considered. The system consists of four different coupling parameters in addition to different phase parameters. The solution of the Heisenberg equations of motion for the dynamical operators is obtained. The phenomenon of squeezing is examined for both normal and principal squeezing and it has been shown that it is more pronounced for the compound mode case. The intensity correlation function is also calculated and discussed where the observation of the antibunching can be reported. In addition to the higher-order moments we examined the quantum correlation functions, joint quasidistribution functions, as well as photon-number distribution and its factorial moments. It has shown that the non-classical properties is apparent of this system and more pronounced for the compound mode (1,3).     

Efficient noncollinear parametric amplification of weak femtosecond pulses in the visible and near-infrared spectral range

We report measurement of efficient amplification of weak femtosecond supercontinuum seed pulses by use of a noncollinear optical parametric process in BBO crystal pumped with 150-fs pulses from a frequency-doubled regenerative-amplified Ti:sapphire laser at 390nm . The highest amplification factor, 10(8) , was achieved for 3x10(-16)J energy seed pulses at wavelength of 560nm.     

Picoradian deflection measurement with an interferometric quasi-autocollimator using weak value amplification

We present an "interferometric quasi-autocollimator" that employs weak value amplification to measure angular deflections of a target mirror. The device has been designed to be insensitive to all translations of the target. We present a conceptual explanation of the amplification effect used by the device. An implementation of the device demonstrates sensitivities better than 10 picoradians per root hertz between 10 and 200 Hz.     

Theory of microwave parametric down-conversion and squeezing using circuit QED

We study theoretically the parametric down-conversion and squeezing of microwaves using cavity quantum electrodynamics of a superconducting Cooper-pair box (CPB) qubit located inside a transmission line resonator. The nonlinear susceptibility chi2 describing three-wave mixing can be tuned by dc gate voltage applied to the CPB and vanishes by symmetry at the charge degeneracy point. We show that the coherent coupling of different cavity modes through the qubit can generate a squeezed state. Based on parameters realized in recent successful circuit QED experiments, squeezing of 95% approximately 13 dB below the vacuum noise level should be readily achievable.     

Cavity-enhanced optical parametric chirped-pulse amplification

A novel method for the generation of high-energy ultrashort optical pulses is described and studied theoretically and numerically. Through the combination of parametric amplification and enhancement cavities, this method opens a route to generate few-cycle pulses at unprecedented average power levels through the use of a low-energy, high average-power pump source and energy storage in the enhancement cavity. Dispersion in the enhancement cavity ceases to be a concern with the use of long pump pulses. Limitations set by the Kerr nonlinearity of the amplifier crystal are analyzed, and ways to overcome them using self-defocusing nonlinearities are discussed.     

Quantum statistics of parametric amplification

Quantum statistical properties of the parametric amplification and generation are investigated. The losses are included and the pump field is treated classically. It is shown that the normal counting generating function decomposes into the product of two functions which are the generating functions for the superposition of coherent and chaotic field and that the outputting field exhibits the anticorrelation effect when the phase of incident fields fulfil a certain condition.The authors thank Mrs A.Mikulecká from Laboratory of Computer Science of Palacký University for performing computations.     

Two-mode squeezing in a coherently driven degenerate parametric down conversion

Squeezing properties of a two-mode radiation produced by a process of driven degenerate parametric down conversion, when the cavity is coupled to two independent squeezed vacuum reservoirs employing the linearization procedure, are analyzed. The two-mode cavity and output radiations exhibit considerable squeezing even when the oscillator is coupled to a vacuum reservoir. One of the effects of coupling the cavity to the squeezed vacuum reservoirs is to increase the degree of squeezing exponentially. For the output radiation the correlation of the quadrature operators evaluated at different times also contributes to the squeezing, which is the reason for quenching of the overall noise in one of the quadrature components of the fundamental mode.     

Quantum statistics of multimode parametric amplification

The effect of a multimode interaction on the squeezing attainable in parametric amplification is investigated. In the non degenerate case the maximum squeezing attainable is reduced from the single mode case, whereas in the degenerate case the squeezing is essentially unaffected by the multimode nature of the interaction.     

Optical parametric amplification from quantum noise

A treatment of optical parametric amplification (OPA) starting from quantum noise is presented. In order to describe the experimental situation the quantum theoretical approach is related to the propagation phenomenon taking into account the multimode character of the parametric radiation. An expression for the initial intensity occurring in the classical formula is derived.     

Self-induced parametric amplification of high-order harmonics

A theoretical analysis of self-induced parametric amplification of high-order harmonics is given. This mechanism permits the elimination of limitations on the harmonic-generation efficiency that are imposed by absorption.     

Stacking chirped pulse optical parametric amplification

Stacking chirped pulse optical parametric amplification based on a home-built Yb³⁺-doped mode-locked fiber laser and an all-fiber pulse stacker has been demonstrated. Energic 11 mJ shaped pulses with pulse duration of 2.3 ns and a net total gain of higher than 1.1 × 10⁷ at fluctuation less than 2% rms are achieved by optical parametric amplification pumped by a Q-switched Nd:YAG frequency-doubled laser, which provides a simple and efficient amplification scheme for temporally shaped pulses by stacking chirped pulse.