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A Single Photon Source for Photon-atom Interaction. Xingxing Xing Centre for Quantum Info. & Quantum Control, Dept. of Physics, Univ. of Toronto. CQISC 2006, Calgary. Group member. Photonics lab @Toronto Rob Adamson Lynden (Krister) Shalm Xingxing Xing Dr. An-Ning Zhang
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A Single Photon Source for Photon-atom Interaction Xingxing Xing Centre for Quantum Info. & Quantum Control, Dept. of Physics, Univ. of Toronto CQISC 2006, Calgary
Group member • Photonics lab @Toronto • Rob Adamson • Lynden (Krister) Shalm • Xingxing Xing • Dr. An-Ning Zhang • Prof. Aephraim Steinberg CQISC 2006, Calgary
Outline • Why single photon source? • Why photon-atom interaction? • How to build up a source? • What could we use the source for? CQISC 2006, Calgary
Motivation • Necessity of a single photon source? • Investigate non-classical behaviors • Use in quant logic, quant crypto., etc. CQISC 2006, Calgary
Motivation • Photons are ideal carrier for Quantum Info Processing and Q. Computation • easy to generate and manipulate • stable: not interact much with environment • LOQC scheme could be essential as part of quantum computation networks • Problems • Photons don’t interact much with envi. hard for storage • Experience losses during commu. reconstruct states • They don’t interact with each other either! two-qubit gates? CQISC 2006, Calgary
Motivation • On the other hand, atoms are good for some aspects: • They interact strongly with each other good candidate for two-qubit gates • Long decoherence time is possible: trapping quantum memory and quantum repeater • Combination of the two: Perfect! CQISC 2006, Calgary
Methods Comparison of Different Schemes of Single photon source CQISC 2006, Calgary
Methods • PDC is good, except for the bandwidth • Make use of cavity: confine the spectrum, also known as Optical Parametric Oscillator (OPO) CQISC 2006, Calgary
Doppler-free Saturated Spectroscopy • Problem: narrow linewidth of atoms: ~6MHz • Doppler shift • The frequency of a moving source/observer is shifted relative to the observer/source. NOTE: the real freq. doesn’t change! • For a moving observer • Vo: speed of observer: positive if the observer is moving away from the source negative if the observer is moving towards the source CQISC 2006, Calgary
Doppler • Stationary and moving source CQISC 2006, Calgary
Doppler effect in photon-atom interaction • Doppler broadening inabsorption profile CQISC 2006, Calgary
OPO Setup CQISC 2006, Calgary
Testing of the laser linewidth CQISC 2006, Calgary
Next step… • Optimize SHG • Setup OPO cavity and optimize it • Play with the source… CQISC 2006, Calgary
Potential Applications • Electromagnetically Induced Transparency (EIT) • Quantum Memory • Quantum Repeater • As a tool to investigate the fundamentals of QM through interaction with cold atoms/BEC • Gap between Classical and quantum world? • Single photon - single atom? • For rent: a single photon source for free space QKD… CQISC 2006, Calgary
EIT • Group velocity & coupling filed • The state of interaction system: photon + atom: CQISC 2006, Calgary
Storage through EIT Fleischhauer, PRL 84, 5094, 2000 CQISC 2006, Calgary
Quantum repeater L.-M., Duan et.al., 414, 413 CQISC 2006, Calgary
Summary • A scheme for narrow bandwidth single-photon source (triggered deterministic) • Such photon-atom interaction could help fill the gap between LCQO and atomic physics • Questions? Comments? Suggestions? CQISC 2006, Calgary