Two-Color Pump-Probe Measurement of Photonic Quantum Correlations Mediated by a Single Phonon

Abstract

We propose and demonstrate a versatile technique to measure the lifetime of the one-phonon Fock state using two-color pump-probe Raman scattering and spectrally resolved, time-correlated photon counting. Following pulsed laser excitation, the n=1 phonon Fock state is probabilistically prepared by projective measurement of a single Stokes photon. The detection of an anti-Stokes photon generated by a second, time-delayed laser pulse probes the phonon population with subpicosecond time resolution. We observe strongly nonclassical Stokes-anti-Stokes correlations, whose decay maps the single phonon dynamics. Our scheme can be applied to any Raman-active vibrational mode. It can be modified to measure the lifetime of n≥1 Fock states or the phonon quantum coherences through the preparation and detection of two-mode entangled vibrational states.

Preparation and Decay of a Single Quantum of Vibration at Ambient Conditions

“…(2) neglects higher-order interactions, in particular, the creation of correlated Stokesanti-Stokes pairs during a single pulse (write or read) via phonon-assisted four-wave mixing [35][36][37][38][39][40]. In our experiment, the photon flux due to this higher-order interaction constitutes an effective background noise [41]. Other extraneous sources of photons, such as from residual χ ð3Þ nonlinearities, or fluorescence, also lead to an excess background noise.…”

“…Setup and measurement procedure Our experimental setup is an upgraded version of that presented in Ref. [41]. Two synchronized laser pulse trains at 810 and 695 nm of duration Δt ≈ 100 fs are produced by a Ti:sapphire oscillator (Tsunami, Spectra Physics, 80-MHz repetition rate) and a synchronously pumped frequency-doubled optical parametric oscillator (OPO-X fs, APE Berlin), respectively.…”

“…These start-stop histograms are used to compute the Stokes-anti-Stokes intensity cross-correlation as explained in Ref. [41]. Therefore, all relevant coincidences required to estimate α are available.…”

Physical Properties of Photonic Cooper Pairs Generated via Correlated Stokes–anti‐Stokes Raman Scattering

“…Equation is valid in resonance with the vibrational transition, i.e., I S,aS is measured at energies matching the S,aS vibrational Raman shifts . This correlated SaS light scattering phenomenon involving the exchange of real phonons has been studied recently in diamond and graphene, evidencing a time correlation at zero delay beyond the maximum classical correlation given by the Cauchy–Schwars inequality, indicating that this phenomenon has no classical analog.…”

Towards a spectroscopic protocol for unambiguous detection of quantum coherence in excitonic energy transport

“…One proposal suggested identifying the quantum behaviour of the vibrational motions that drive EET via phonon antibunching [6]. This however requires coherent ultrafast phonon spectroscopy which remains challenging [23]. We therefore focus on a quantifier of quantum coherence that is experimentally accessible via non-linear ultrafast optical spectroscopy.…”