Interferometric Measurement of the Biphoton Wave Function

Beduini, Federica A.; Zielińska, Joanna A.; Lucivero, Vito Giovanni; Astiz, Yannick A. de Icaza; Mitchell, Morgan W.

doi:10.1103/physrevlett.113.183602

Cited by 36 publications

(31 citation statements)

References 31 publications

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“…This method can also be applied to narrow-band biphotons generated from cavity-enhanced spontaneous parametric down-conversion [17]. Note added.-We became aware that during the review process a work of measuring the biphoton temporal wave function using a homodyne method was published [37]. Our method of polarization-dependent and time-resolved two-photon interference is different and does not require any external reference.…”

Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

Measuring the Biphoton Temporal Wave Function with Polarization-Dependent and Time-Resolved Two-Photon Interference

et al. 2015

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We propose and demonstrate an approach to measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference. Through six sets of two-photon interference measurements projected onto different polarization subspaces, we can reconstruct the amplitude and phase functions of the biphoton temporal waveform. For the first time, we apply this technique to experimentally determine the temporal quantum states of the narrow-band biphotons generated from the spontaneous four-wave mixing in cold atoms. DOI: 10.1103/PhysRevLett.114.010401 PACS numbers: 03.65.Wj, 03.67.Mn, 42.50.Dv Photons are described by their discrete polarization states and field amplitude distribution in continuous time-space domains. The state density matrix in a discrete Hilbert space can be reconstructed using the well-developed quantum-state tomography [1][2][3][4]. To describe the temporal modes of photons, one needs a continuous-variable quantum-state tomography characterizing both the amplitude and the phase functions. Homodyne detection has been proven an efficient probe to characterize photonic (unentangled) Fock and coherent states [5][6][7][8][9][10]. However, most homodyne measurements of bipartite states have only aimed at verifying the entanglement [11][12][13][14][15]. A complete optical homodyne tomography for the time-frequency entangled two-photon (amplitude and phase) temporal waveform still remains a technical challenge [8].There is an increasing interest in fully characterizing narrow-band biphotons because of their applications in realizing efficient light-matter quantum interfaces [16][17][18][19]. Using spontaneous four-wave mixing (SFWM) in cold atoms [20], the sub-MHz biphoton generation with a coherence time on the order of microseconds has been demonstrated [21][22][23]. Such a long coherence time of single photons allows manipulating their temporal waveforms [24][25][26] and their interaction with atoms in the time domain [27][28][29]. Owning to the nanosecond time resolution of commercially available single-photon counting modules (SPCM), the biphoton amplitude temporal profile can be directly measured from the coincidence counts. However, the coincidence counting does not distinguish between a time-frequency entangled state and a temporal-probability mixed state because it does not measure the phase distribution. Although additional evidences, such as the violation of the Cauchy-Schwarz inequality [30] and the antibunching of heralded single photons [31] can indicate the nonclassical properties, they do not provide a complete state information. It is believed that the time-frequency entanglement of biphotons generated from a continuouswave SFWM is naturally endowed by the energy conservation [32], but this claim has not been confirmed experimentally.In this Letter, we propose and implement a technique to measure the temporal wave function of SFWM narrowband biphotons. Using six sets of symmetrized timeresolved two-photon interference measurements in different polarization...

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Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

Measuring the Biphoton Temporal Wave Function with Polarization-Dependent and Time-Resolved Two-Photon Interference

et al. 2015

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“…1 (a). A polarization-squeezed probe beam is generated as in [36] by combining local oscillator (LO) laser light with orthogonally polarized squeezed vacuum using a parametric oscillator described in [37], cavity locking system as in [38], and a quantum noise lock (to ensure the measured Stokes component is the squeezed component) described in [33,39]. The probe frequency is stabilized to 20 GHz to the blue of the 85 Rb D 1 unshifted line using the system of [40].…”

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confidence: 99%

Squeezed-light spin noise spectroscopy

et al. 2016

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We report quantum enhancement of Faraday rotation spin noise spectroscopy by polarization squeezing of the probe beam. Using natural abundance Rb in 100 Torr of N2 buffer gas, and squeezed light from a sub-threshold optical parametric oscillator stabilized 20 GHz to the blue of the D1 resonance, we observe that an input squeezing of 3.0 dB improves the signal-to-noise ratio by 1.5 dB to 2.6 dB over the combined (power)⊗(number density) ranges (0.5 mW to 4.0 mW)⊗(1.5 ×10 12 cm −3 to 1.3 ×10 13 cm −3 ), covering the ranges used in optimized spin noise spectroscopy experiments. We also show that squeezing improves the trade-off between statistical sensitivity and broadening effects, a previously unobserved quantum advantage.The presence of intrinsic fluctuations of a spin system in thermal equilibrium was first predicted by Bloch [1] and experimentally demonstrated in the 1980's by Aleksandrov and Zapasskii [2]. In the last decade, "spin noise spectroscopy" (SNS) has emerged as a powerful technique for determining physical properties of an unperturbed spin system from its noise power spectrum [3,4]. SNS has allowed measurement of g-factors, nuclear spin, isotope abundance ratios and relaxation rates of alkali atoms [5,6], g-factors, relaxation times and doping concentration of electrons in semiconductors [7][8][9][10][11] and localized holes in quantum dot ensembles [12,13] including single hole spin detection [14]. Recently, SNS has been used to study complex optical transitions and broadening processes [15,16], coherent phenomena beyond linear response [17] and cross-correlations of heterogeneous spin systems [18,19].Spin noise has been measured with nuclear magnetic resonance [20,21] and magnetic force microscopy [22][23][24], but the most sensitive and widely used detection technique is Faraday rotation (FR) [2,5,6], in which the spin noise is mapped onto the polarization of an off-resonant probe. In FR-SNS, spin noise near the Larmor frequency competes with quantum noise [25] of the detected photons, i.e., the optical shot noise. The main figure of merit is η, the peak power spectral density (PSD) due to spin noise over the PSD due to shot noise, called "signal strength" [26] or the "signal-to-noise ratio" (SNR). Reported SNR for single-pass atomic ensembles ranges from 0 dB to 13 dB [5,27], and up to 21 dB in atomic multi-pass cells [28]. Due to weaker coupling to the probe beam, reported SNR ranges from −50 dB to −20 dB in semiconductor systems (See Table 1 in [26]). Several works have studied how to improve the polarimetric sensitivity [29] or to cancel technical noise sources [7,8,10], but without altering the fundamental tradeoff between sensitivity and broadening processes [29].For small optical power P and atomic density n, SNR is linear in each: η ∝ nP . At higher values, light scattering and atomic collisions broaden the spin noise resonances, and thus introduce systematic errors in measurements, e.g. of relaxation rates, that are derived from the SNS linewidth [5][6][7]. This trade-off between statis...

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“…Most recently, it was demonstrated that a single photon with time-reversed exponential growth waveform can be loaded into a single-sided Fabry Pérot cavity with near-unity ef-ficiency [102,103]. With the time-resolved quantum-state tomography [104,105], their further applications in quantum network and quantum information processing are to be explored.…”

Section: Discussionmentioning

confidence: 99%

Narrowband Biphotons: Generation, Manipulation, and Applications

Chuu

2015

Engineering the Atom-Photon Interaction

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In this chapter, we review recent advances in generating narrowband biphotons with long coherence time using spontaneous parametric interaction in monolithic cavity with cluster effect as well as in cold atoms with electromagnetically induced transparency. Engineering and manipulating the temporal waveforms of these long biphotons provide efficient means for controlling light-matter quantum interaction at the single-photon level. We also review recent experiments using temporally long biphotons and single photons.

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Interferometric Measurement of the Biphoton Wave Function

Cited by 36 publications

References 31 publications

Measuring the Biphoton Temporal Wave Function with Polarization-Dependent and Time-Resolved Two-Photon Interference

Measuring the Biphoton Temporal Wave Function with Polarization-Dependent and Time-Resolved Two-Photon Interference

Squeezed-light spin noise spectroscopy

Narrowband Biphotons: Generation, Manipulation, and Applications

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