Quantum State Reconstruction of the Single-Photon Fock State

Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany.
Physical Review Letters (Impact Factor: 7.51). 07/2001; 87(5):050402. DOI: 10.1103/PhysRevLett.87.050402
Source: PubMed


We have reconstructed the quantum state of optical pulses containing single photons using the method of phase-randomized pulsed optical homodyne tomography. The single-photon Fock state 1> was prepared using conditional measurements on photon pairs born in the process of parametric down-conversion. A probability distribution of the phase-averaged electric field amplitudes with a strongly non-Gaussian shape is obtained with the total detection efficiency of (55+/-1)%. The angle-averaged Wigner function reconstructed from this distribution shows a strong dip reaching classically impossible negative values around the origin of the phase space.

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    • "As such, its statistics feature substantial yet temporally fluctuating bunching of photons, making it a perfect test case for the photon number resolving capabilities of our setup. ii) Heralded single photons from a spontaneous parametric down conversion source, which approximately represent the ideal scenario of single-photon Fock states [31]. In the multiplexer, classical coherent states |ψ in = |α are split into eight spatially separated coherent states of equal amplitude, i.e. |ψ out = "
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    ABSTRACT: The key requirement for harnessing the quantum properties of light is the capability to detect and count individual photons. Of particular interest are photon-number-resolving detectors, which allow one to determine whether a state of light is classical or genuinely quantum. Existing schemes for addressing this challenge rely on a proportional conversion of photons to electrons. As such, they are capable of correctly characterizing small photon fluxes, yet are limited by uncertainties in the conversion rate. In this work, we employ a divide-and-conquer approach to overcome these limitations by transforming the incident fields into uniform distributions that readily lend themselves for characterization by standard on-off detectors. Since the exact statistics of the light stream are obtained from the click statistics, our technique is freely scalable to accommodate - in principle - arbitrarily large photon fluxes. Our experiments pave the way towards genuine integrated photon-number-resolving detectors for advanced on-chip photonic quantum networks.
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    • "To the best of our knowledge, no detailed studies have yet been done of the phase space evolution of ultracold atoms in anharmonic potentials; furthermore, real-space dynamical studies in anharmonic traps have heretofore been done at temperatures and/or densities where small nano-Kelvin disorders are not expected to play a significant role [21] [22]. Tomography provides a method to reconstruct such phase space distributions from experimental data [23], as has been demonstrated for photonic states [24] and for an atomic beam [25]. "
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    ABSTRACT: We demonstrate tomographic reconstruction of the phase space distribution of atoms oscillating in a harmonic trap with weak potential corrugation caused by nanoscale imperfections in an atomchip. We find that deformations in these distributions are highly sensitive to anharmonic components of the potential. They are explained in terms of angular velocity dispersion of isoenergetic phase space trajectories. We show that the method is applicable for probing classical and quantum dynamics of cold atoms, and we note its importance for future technological applications.
    Physical Review A 09/2014; 90:033620. DOI:10.1103/PhysRevA.90.033620 · 2.81 Impact Factor
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    • "In Fig. 2(b), the quadrature samples and their histogram corresponding to the envelope function ψ(t) are presented. There is a dip at the center of the histogram, which is a characteristic of a single-photon state [17] [18]. By performing maximum likelihood estimation on the quadrature distribution [35], we obtained the Wigner function [Fig. "
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    ABSTRACT: Highly nonclassical quantum states of light, characterized by Wigner functions with negative values, have been created so far only in a heralded fashion. In this case, the desired output emerges rarely and randomly from a quantum-state generator. An important example is the heralded production of high-purity single-photon states, typically based on some nonlinear optical interaction. In contrast, on-demand single-photon sources were also reported, exploiting the quantized level structure of matter systems. These sources, however, lead to highly impure output states, composed mostly of vacuum. While such impure states may still exhibit certain single-photon-like features such as anti-bunching, they are not enough nonclassical for advanced quantum information processing. On the other hand, the intrinsic randomness of pure, heralded states can be circumvented by first storing and then releasing them on demand. Here we propose such a controlled release, and we experimentally demonstrate it for heralded single photons. We employ two optical cavities, where the photons are both created and stored inside one cavity, and finally released through a dynamical tuning of the other cavity. We demonstrate storage times of up to 300 ns, while keeping the single-photon purity around 50% after storage. This is the first demonstration of a negative Wigner function at the output of an on-demand photon source or a quantum memory. In principle, our storage system is compatible with all kinds of nonclassical states, including those known to be essential for many advanced quantum information protocols.
    Physical Review X 09/2013; 3(4). DOI:10.1103/PhysRevX.3.041028 · 9.04 Impact Factor
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