* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download FOI2013Poster
Quantum computing wikipedia , lookup
EPR paradox wikipedia , lookup
History of quantum field theory wikipedia , lookup
Interpretations of quantum mechanics wikipedia , lookup
Wheeler's delayed choice experiment wikipedia , lookup
Quantum group wikipedia , lookup
Quantum teleportation wikipedia , lookup
X-ray fluorescence wikipedia , lookup
Bell's theorem wikipedia , lookup
Coherent states wikipedia , lookup
Quantum machine learning wikipedia , lookup
Wave–particle duality wikipedia , lookup
Hidden variable theory wikipedia , lookup
Canonical quantization wikipedia , lookup
Bohr–Einstein debates wikipedia , lookup
Quantum state wikipedia , lookup
Theoretical and experimental justification for the Schrödinger equation wikipedia , lookup
Two-dimensional nuclear magnetic resonance spectroscopy wikipedia , lookup
Quantum key distribution wikipedia , lookup
Spectral density wikipedia , lookup
Double-slit experiment wikipedia , lookup
Optical amplifier wikipedia , lookup
Quantum and classical photon correlation in four wave mixing and CARS spectroscopy Rafi Z. Vered, Yelena Ben-Or, Michael Rosenbluh and Avi Pe’er Department of Physics and BINA Center for Nano-technology, Bar-Ilan University, Ramat-Gan 52900, Israel Abstract: We demonstrate two-photon interference with correlated photon pairs produced by FWM. We explore the quantum-classical transition of the light by observing the loss dependence of the interference contrast for various pump intensities. Experimental concept: Introduction: In degenerate (FWM), a pump field at frequency 𝜔𝑝 is converted through a third-order non linearity, to another pair of frequencies 𝜔𝑠 , 𝜔𝑖 (signal and idler) so that energy and momentum are conserved 2𝜔𝑝 = 𝜔𝑠 + 𝜔𝑖 , 2𝑘𝑝 ≈ 𝑘𝑠 + 𝑘𝑖 . p i 3 s p p p i s The pump, signal and idler relative phase relationship (𝜙𝑡𝑜𝑡𝑎𝑙 = 𝜙𝑠 + 𝜙𝑖 − 2𝜙𝑝 ) dictate the direction of energy flow (from pump to signal/idler light or vice versa). idler signal For 𝜙𝑡𝑜𝑡𝑎𝑙 = 0 For 𝜙𝑡𝑜𝑡𝑎𝑙 = 𝜋 the energy flows from the pump to signal and idler. the energy flows from signal and idler to pump. Dispersive window st 1 nd 2 FWM s p A dispersive window imposes a spectrally modulated relative phase, causing interference fringes to appear on the FWM spectrum. , FWM is an amplification process, and its fringe contrast is expected to be tanh 𝑔, where the gain 𝑔 is dictated by the pump intensity during the 2nd FWM pass. , this two-photon interference can reveal the quantum nature of the signal-idler light in a simple way. Pump beam Two-photon BS Pump Laser Ti:Sapphire Two-photon BS 𝜑 𝜔 0 FWM beam Experimental setup: FWM i Isolator Dispersive window 2nd attenuator 6ps pump pulses at 784nm enter a 12 cm long photonic crystal fiber (PCF), 1st attenuator with zero dispersion at 783nm, generating signal-idler pairs over a broad frequency range. After the first pass through the fiber the pump and the PCF signal-idler pairs are reflected back for a second pass through the fiber. In Dichroic BS Spectrometer between, a dispersive window modulates the spectral phase of the signalClassically, these two scenarios are equivalent, but quantum idler pairs compared to the pump, causing the appearance of spectral mechanically, they are very different, as pump attenuation before the first fringes. The resulting FWM spectrum is measured on a high resolution FWM reduces the bi-photon flux, but leaves their correlations intact, spectrometer. whereas attenuation between the passes (loss) hampers the correlation : attenuating the pump before the fiber. severely. Thus, the fringe contrast in the first scenario is considerably : attenuating the pump and FWM between the higher than in the second scenario, providing a measure of the nonpasses. classicality of the light. Results: Fringe contrast 1 Signal spectrum (attenuation between passes) ~0% 5% 10% 15% ~0% 5% 10% 15% 0.8 Contrast Signal spectrum (attenuation before the fiber) 0.6 0.4 attenuation before the fiber attenuation between the passes 0.2 0 680 700 720 740 680 700 720 740 (a) Measured spectral interference when attenuation is applied before the fiber. (b) The same interference when attenuation is applied between the passes through the fiber. Both graphs present the same four measurable lowest pump intensities. 0 50 Pump Intensity (mW) 100 150 The measured fringe contrast as a function of the pump power after the 2nd pass scanned down from 150mW (average power) in two ways, either by attenuating the pump before both passes (red) or by attenuation between the passes (blue). Up to 60mW pump power (close to the calculated value, due to time correlation measurements[1]) , marking the transition between the quantum regime of single bi-photons at low pump powers and the multi-photon semi-classical regime at high powers. [1] Rafi Z. Vered, Michael Rosenbluh, and Avi Pe’er, "Two-photon correlation of broadbandamplified spontaneous four-wave mixing", Phys. Rev. A 86, 043837 (2012). A simple two-photon interference method has been demonstrated for investigating the quantum correlation of broadband bi-photons generated by FWM. Due to the high gain of our PCF fiber, we fully observe the transition between quantum and classical regimes. The collinear, in fiber arrangement makes the experimental configuration inherently robust to phase fluctuations and does not require any phase locking to observe a stable fringe pattern, thereby considerably simplifying the measurement. We expect this method to be useful as an additional tool in the quantum optics and quantum information toolbox.