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Title  Category  Date  Authors 
Tomography of a HighPurity Narrowband Photon from a Transient Atomic Collective Excitation University of Calgary, University of Alberta  Publication  20120701  A. MacRae, T. Brannan, R. Achal, A. Lvovsky  Towards engineering arbitrary superpositions of collective spin excitations University of Calgary, University of Alberta  Presentation  20120723  T. Brannan, A. MacRae, R. Achal, A. Lvovsky  Tomography of single photons and qubits generated by atoms University of Calgary, University of Alberta  Presentation  20120704  A. MacRae, T. Brannan, R. Achal, A. Lvovsky  Generation of arbitrary quantum states from atomic ensembles University of Calgary, University of Alberta  Presentation  20120611  A. MacRae, T. Brannan, R. Achal, A. Lvovsky  Tomography of a highpurity narrowband photon from fourwave mixing in atomic vapourMuch work has been done in recent years to develop interesting quantum states in the optical regime. A natural step forward would be to extend our quantum state engineering abilities to collective spin excitations (CSE’s) in hot atomic vapour. Such an extension could find applications in quantum memory, long distance quantum communication, quantum logic gates, and quantum metrology. We demonstrate a setup that serves as a high quality single photon source and a first step towards quantum state engineering of arbitrary states in CSE’s.
We use fourwave mixing in a hot atomic vapour cell to create a twomode squeezed state, similar to parametric down conversion. Heralding on a single photon event in one channel yields a high purity narrowbandwidth single photon in the other channel. Employing optical homodyne tomography, we reconstruct the density matrix of the generated photon and observe a Wigner function reaching the zero value without correcting for inefficiencies. The intrinsic narrow bandwidth and high production rate of our system result in a high spectral brightness source. Since these photons are also naturally resonant to atomic transitions, our source is attractive for applications in lightatom interfacing.
Moving to the pulsed regime would allow for time separated events of CSE creation and optical readout, akin to the wellknown DLCZ scheme. Conditional measurements during the write phase prepare the CSE in an arbitrary superposition state, which can then be read out optically and measured via homodyne tomography.
University of Calgary, University of Alberta  Presentation  20120816  T. Brannan, A. MacRae, R. Achal, A. Lvovsky  Generation of arbitrary quantum states from atomic ensembles University of Calgary, University of Alberta  Publication  20120901  A. MacRae, T. Brannan, R. Achal  Single photons generated by atoms University of Calgary, University of Alberta  Presentation  20120523  A. MacRae, T. Brannan, P. Palittapongarnpim, R. Achal, A. Lvovsky 

