Article

A photonic quantum information interface

Group of Applied Physics, University of Geneva, 1211 Geneva 4, Switzerland.
Nature (Impact Factor: 42.35). 08/2005; 437(7055):116-120. DOI: 10.1038/nature04009
Source: arXiv

ABSTRACT Quantum communication requires the transfer of quantum states, or quantum bits of information (qubits), from one place to another. From a fundamental perspective, this allows the distribution of entanglement and the demonstration of quantum non-locality over significant distances. Within the context of applications, quantum cryptography offers a provably secure way to establish a confidential key between distant partners. Photons represent the natural flying qubit carriers for quantum communication, and the presence of telecommunications optical fibres makes the wavelengths of 1,310 nm and 1,550 nm particularly suitable for distribution over long distances. However, qubits encoded into alkaline atoms that absorb and emit at wavelengths around 800 nm have been considered for the storage and processing of quantum information. Hence, future quantum information networks made of telecommunications channels and alkaline memories will require interfaces that enable qubit transfers between these useful wavelengths, while preserving quantum coherence and entanglement. Here we report a demonstration of qubit transfer between photons of wavelength 1,310 nm and 710 nm. The mechanism is a nonlinear up-conversion process, with a success probability of greater than 5 per cent. In the event of a successful qubit transfer, we observe strong two-photon interference between the 710 nm photon and a third photon at 1,550 nm, initially entangled with the 1,310 nm photon, although they never directly interacted. The corresponding fidelity is higher than 98 per cent.

Download full-text

Full-text

Available from: Hugo Zbinden, Jul 28, 2015
0 Followers
 · 
153 Views
  • Source
    • "Therefore, the future of quantum nodes very likely depends on the ability to realize hybrid quantum systems, coupling standard photonic and matter based devices, having coherently and efficiently matched spectral properties. In this framework the nonlinear optical processes of sum and difference frequency generation are expected to play a more and more important role [11] [12]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We report a teleportation experiment involving narrowband entangled photons at 1560 nm and qubit photons at 795 nm emulated by faint laser pulses. A nonlinear difference frequency generation stage converts the 795 nm photons to 1560 nm in order to enable interference with one photon out of the pairs, i.e., at the same wavelength. The spectral bandwidth of all involved photons is of about 25 MHz, which is close to the emission bandwidth of emissive quantum memory devices, notably those based on ensembles of cold atoms and rare earth ions. This opens the route towards the realization of hybrid quantum nodes, i.e., combining quantum memories and entanglement-based quantum relays exploiting either a synchronized (pulsed) or asynchronous (continuous- wave) scenario.
    IEEE Journal of Selected Topics in Quantum Electronics 12/2014; 21(3). DOI:10.1109/JSTQE.2014.2381465 · 3.47 Impact Factor
  • Source
    • "Ultrafast laser pulses and nonlinear optics provide a framework for single-photon measurement on timescales much faster than electronics [10] [11]. A promising coherent nonlinear effect for single-photon ultrafast measurements is sum-frequency generation (SFG), a process in which two pulses interact in a nonlinear material to produce a third with frequency equal to the sum of the inputs [12] [13] [14] [15]. SFG in conjunction with pulse-shaping techniques is a powerful tool for manipulating singlephoton temporal waveforms [16] [17] [18]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Time-bin encoding is a robust form of optical quantum information, especially for transmission in optical fibers. To readout the information, the separation of the time bins must be larger than the detector time resolution, typically on the order of nanoseconds for photon counters. In the present work, we demonstrate a technique using a nonlinear interaction between chirped entangled time-bin photons and shaped laser pulses to perform projective measurements on arbitrary time-bin states with picosecond-scale separations. We demonstrate a tomographically complete set of time-bin qubit projective measurements and show the fidelity of operations is sufficiently high to violate the Clauser-Horne-Shimony-Holt-Bell inequality by more than 6 standard deviations.
    Physical Review Letters 10/2013; 111(15):153602. DOI:10.1103/PhysRevLett.111.153602 · 7.51 Impact Factor
  • Source
    • "The intrinsic dark count rate is very low, and is usually negligible in comparison to the noise due to the frequency conversion process. It is widely believed that the noise which arises in the frequency conversion process stems from the spontaneous Raman scattering (SRS) [Diamanti et al., 2005; Langrock et al., 2005; Thew et al., 2006; Tanzilli et al., 2005; Xu et al., 2007; Vandevender & Kwiat, 2004] and spontaneous parametric down conversion (SPDC) [Pelc et al, 2010] generated in the waveguide by the strong pump. If these SRS photons or SPDC photons are generated at wavelengths within the signal band they can be up-converted to the detection wavelength, generating noise or 'dark' counts. "
    Photodiodes - Communications, Bio-Sensings, Measurements and High-Energy Physics, 09/2011; , ISBN: 978-953-307-277-7
Show more