Introduction We are an experimental quantum optics group run by Kevin Resch, based in the Department of Physics & Astronomy and the Institute for Quantum Computing at the University of Waterloo.
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Our paper entitled, Spectral compression of single photons by Jonathan Lavoie, John Donohue, Logan Wright, Alessandro Fedrizzi (U. Queensland), and Kevin Resch, was published in Nature Photonics.
Abstract: Photons are critical to quantum technologies because they can be used for virtually all quantum information tasks, for example, in quantum metrology, as the information carrier in photonic quantum computation, as a mediator in hybrid systems, and to establish long-distance networks. The physical characteristics of photons in these applications differ drastically; spectral bandwidths span 12 orders of magnitude from 50 THz for quantum-optical coherence tomography to 50 Hz for certain quantum memories. Combining these technologies requires coherent interfaces that reversibly map centre frequencies and bandwidths of photons to avoid excessive loss. Here, we demonstrate bandwidth compression of single photons by a factor of 40 as well as tunability over a range 70 times that bandwidth via sum-frequency generation with chirped laser pulses. This constitutes a time-to-frequency interface for light capable of converting time-bin to colour entanglement, and enables ultrafast timing measurements. It is a step towards arbitrary waveform generation for single and entangled photons.
…to Jonathan for being chosen for an NSERC PDF and an IQC achievement award!
…to Deny for being selected for a 2013 UW Physics Special Graduate Scholarship and an IQC achievement award!
…to Kent for winning the Governor General Gold Medal for his outstanding MSc work!
…to Mike for successful completion of his MSc!
Update June 17, 2013 …to Kent for also winning the Dean of Science Award for his MSc work!
Update August 9, 2013 …to Jonathan for successfully defending his PhD!
A new paper, Experimental violation of three families of Bell’s Inequalities by Lydia Vermeyden, Madeleine Bonsma, Crystal Noel, John Donohue, Elie Wolfe, and Kevin Resch was just published in Physical Review A.
Abstract: Bell’s inequalities are important to our understanding of quantum foundations and critical to several quantum technologies. A recent work [ E. Wolfe and S. F. Yelin Phys. Rev. A 86 012123 (2012)] derived three parametrized families of two-particle, two-setting Bell inequalities. These inequalities are important as they theoretically explore a larger volume of allowed quantum correlations over local hidden-variable models than previous results [ A. Cabello Phys. Rev. A 72 012113 (2005)] by exploiting marginal, or single particle measurements. In this work we subject those predictions to experimental test using nonmaximally entangled photon pairs to optimize the expected violation. We find excellent agreement with the upper bounds predicted by quantum mechanics with violations of the limits imposed by local hidden-variable models as large as almost 30σ for the optimal parameters and a significant violation over a wide range of parameters.
A new paper Three-photon energy time entanglement by Krister Shalm, Deny Hamel, Zhizhong Yan, Christophe Simon (U Calgary), Kevin Resch, and Thomas Jennewein appeared in Nature Physics advance online publication today.
Story on IQC website.
Update Jan 31, 2013: Research Highlights in Nature Photonics, Tripartite entanglement by Noriaki Horiuchi.
Lydia Vermeyden and Megan Agnew have joined the group as MSc students; Madeleine Bonsma is working with us for her co-op work term. Welcome all!
Kent Fisher won the prestigious NSERC Vanier Fellowship to fund his graduate studies. Congratulations Kent!
From NSERC website:
The Vanier CGS program aims to attract and retain world-class doctoral students by supporting students who demonstrate both leadership skills and a high standard of scholarly achievement in graduate studies in the natural sciences and engineering, social sciences and humanities, or health sciences. Both Canadian and international students are eligible to be nominated for a Vanier Canada Graduate Scholarship.
Story on IQC website
Chris Erven has joined the group as a post-doctoral fellow; John Dengis (University of Waterloo) and Crystal Noel (MIT) have joined the group as undergraduate researchers for the summer. Welcome all!
A new paper, Optimal linear optical implementation of a single-qubit damping channel by Kent Fisher, Robert Prevedel, Rainer Kaltenbaek, and Kevin Resch, was just published in the New Journal of Physics.
Abstract: We experimentally demonstrate a single-qubit decohering quantum channel using linear optics. We implement the channel, whose special cases include the familiar amplitude-damping channel and the bit-flip channel, using a single, static optical setup. Following a recent theoretical result (Piani et al 2011 Phys. Rev. A 84 032304), we realize the channel in an optimal way, maximizing the probability of success, i.e. the probability for the photonic qubit to remain in its encoding. Using a two-photon entangled resource, we characterize the channel using ancilla-assisted process tomography and find average process fidelities of 0.98 ± 0.01 and 0.976 ± 0.009 for amplitude-damping and the bit-flip case, respectively.
Our paper, Classical analog for dispersion cancellation of entangled photons with local detection, was published online today in Physical Review A.
Abstract: Energy-time entangled photon pairs remain tightly correlated in time when the photons are passed through equal magnitude, but opposite in sign, dispersion.Arecent experimental demonstration has observed this effect on ultrafast time scales using second-harmonic generation of the photon pairs. However, the experimental signature of this effect does not require energy-time entanglement. Here, we demonstrate a direct analogue to this effect in narrow-band second-harmonic generation of a pair of classical laser pulses under similar conditions. Perfect cancellation is observed for fs pulses with dispersion as large as 850 fs^2, comparable to the quantum result, but with an 10^13-fold improvement in signal brightness.
 Our paper, Experimental investigation of the uncertainty principle in the presence of quantum memory and its application to witnessing entanglement, by Robert Prevedel, Deny Hamel, Roger Colbeck (Perimeter Institute), Kent Fisher, and Kevin Resch was published online today in Nature Physics.
Update Oct14, 2011: The paper has appeared in the print version this month, Nature Physics 7, 757 (2011).
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