Direct observation of the degree of correlations using photon-number-resolving detectors

Abstract

Optical parametric down-conversion is a common source for the generation of non-classical correlated photonic states. Using a parametric down-conversion source and photon-number resolving detectors, we measure the two-mode photon-number distribution of up to 10 photons. By changing the heralded collection efficiency, we control the level of correlations between the two modes. Clear evidence for photon-number correlations are presented despite detector imperfections such as low detection efficiency and other distorting effects. Two criteria, derived directly from the raw data, are shown to be good measures for the degree of correlation. Additionally, using a fitting technique, we find a connection between the measured photon-number distribution and the degree of correlation of the reconstructed original two-mode state. These observations are only possible as a result of the detection of high photon number events.PACS numbers: 42.50. Ar, 42.50.Dv, 42.65.Lm Non-classical states of light are an essential resource for novel protocols in quantum information and quantum metrology [1,2]. The most common tool for producing such states is the nonlinear process of optical parametric down-conversion (PDC). In this process, a parent pump photon is split in a nonlinear material into two daughter down-converted photons, while conserving energy and momentum. As the down-converted photons originate from a single quantum system, they possess correlations in many degrees of freedom, such as their polarization, frequency and momentum. Because for any photon emitted into one optical mode there is a sister photon emitted into the other optical mode, there are also photon-number correlations between the two modes. These correlations have been used to produce heralded Fock states [3][4][5] and enhance the precision of optical measurements [1,2,6,7].

Uncovering Quantum Correlations with Time-Multiplexed Click Detection

“…The resulting parameters are fitted: ξ 0 = 0.087 (µW) −1/2 , η = 0.096, and ν = 0.51. (16) The relation between the squeezing parameter and the mean photon number is n = ξ|n A + nB |ξ = 2 sinh 2 ξ or ξ = arsinh n/2 . (17)…”

“…Various kinds of such photonnumber-resolving detectors have been implemented to demonstrate nonclassical features of radiation fields, e.g., in Refs. [11][12][13][14][15][16][17], or for characterizing the non-Poissonian behavior of the click statistics [18,19]. One particular realization of such a scheme that requires only a small number of optical elements is so-called time-bin multi- The realization of two TMDs in a single device is depicted.…”

Statistics of twin-beam states by photon-number resolving detectors up to pump depletion

“…Many experimental works, performed in very different intensity regimes and with different kinds of detectors, are aimed at characterizing the properties of TWB states, mainly concerning photon-number statistics [4][5][6][7][8][9][10] and correlations [11][12][13][14][15][16]. In fact, TWB states both at single-and at multiphoton levels exhibit strong nonclassical correlations between the two parties in several degrees of freedom (linear position and momentum, frequency, polarization, angular momentum, etc.)…”

Quantum state features of the FEL radiation from the occupation number statistics

“…In the latter case, photon-counting techniques have many drawbacks, as evidenced by [6] in the case of [5]. In general, they are limited to the detection of up to few tens of photons [15][16][17][18][19]. If the average number of photons increases, as in the case of high intensity sources, photon counting becomes challenging, even for attenuated FEL radiation.…”