Do you want to publish a course? Click here

Quantum interferences reconstruction with low homodyne detection efficiency

104   0   0.0 ( 0 )
 Added by Martina Esposito
 Publication date 2015
  fields Physics
and research's language is English




Ask ChatGPT about the research

Standard quantum state reconstruction techniques indicate that a detection efficiency of $0.5$ is an absolute threshold below which quantum interferences cannot be measured. However, alternative statistical techniques suggest that this threshold can be overcome at the price of increasing the statistics used for the reconstruction. In the following we present numerical experiments proving that quantum interferences can be measured even with a detection efficiency smaller than $0.5$. At the same time we provide a guideline for handling the tomographic reconstruction of quantum states based on homodyne data collected by low efficiency detectors.

rate research

Read More

Most quantum key distribution (QKD) protocols could be classified as either a discrete-variable (DV) protocol or continuous-variable (CV) protocol, based on how classical information is being encoded. We propose a protocol that combines the best of both worlds: the simplicity of quantum state preparation in DV protocols as well as the cost-effective and high bandwidth of homodyne detectors that are normally used in CV protocols. In addition, our protocol does not require the honest parties to share the same reference phase, in contrast to typical CV-QKD protocols. We then prove the security of the proposed protocol in the asymptotic limit under the assumption of collective attacks. Our simulation suggests that the protocol is suitable for secure and high-speed practical key distribution over short distances.
Controlling the quadrature measured by a homodyne detector is a universal task in continuous-variable quantum optics. However, deriving an error signal that is linear across theentire range of quadrature angles remains an open experimental problem. Here we propose a scheme to produce such an error signal through the use of a universally tunable modulator.
We report an experimental quantum key distribution that utilizes balanced homodyne detection, instead of photon counting, to detect weak pulses of coherent light. Although our scheme inherently has a finite error rate, it allows high-efficiency detection and quantum state measurement of the transmitted light using only conventional devices at room temperature. When the average photon number was 0.1, an error rate of 0.08 and effective quantum efficiency of 0.76 were obtained.
98 - A. I. Lvovsky 2003
I propose an iterative expectation maximization algorithm for reconstructing a quantum optical ensemble from a set of balanced homodyne measurements performed on an optical state. The algorithm applies directly to the acquired data, bypassing the intermediate step of calculating marginal distributions. The advantages of the new method are made manifest by comparing it with the traditional inverse Radon transformation technique.
We suggest and demonstrate a scheme to reconstruct the symmetric two-mode squeezed thermal states of spectral sideband modes from an optical parametric oscillator. The method is based on a single homodyne detector and active stabilization of the cavity. The measurement scheme have been successfully tested on different two-mode squeezed thermal states, ranging from uncorrelated coherent states to entangled states.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا