## Research

### Quantum Computing

Today's computers operate using the binary system, in which information is encoded as bits which can be either 0 or 1. According to quantum mechanics, a physical system can be in a superposition of states, with amplitudes that are represented by complex numbers. By building a computer from quantum bits, or qubits, it is possible to take advantage of these amplitudes to solve some problems exponentially faster than conventional computers.

As quantum particles, photons have the properties necessary to act as qubit. They also have the advantage of being easily transmitted over great distances without being disturbed by their environment. They can therefore be used as one of the basic elements for the construction of quantum computers.

### Entangled photon sources

One of the properties that distinguishes quantum systems is that they can have much stronger correlations than classical physics predicts. For example, two photons that are measured several light-years apart from one another could give perfectly correlated measurement results. These correlations are called quantum entanglement. Quantum entanglement is one of the important resources that is useful for quantum information technologies.

For photons to be entangled in a useful way, they must be created in a very particular way. In our labs, we use parametric downconversion, which divides photons in two into nonlinear crystals to create entangled states of photons.

## Group Members

Deny Hamel joined Université de Moncton in 2014. He is an associate professor and Canada Research Chair in Optics and Quantum Information. |
Samridhi Gambhir is a postdoctoral researcher. Her work includes working on quantum information applications of cascaded SPDC. |

Bobby Bourque is currently finishing his MSc work studying second harmonic generation at low photon levels in organic nonlinear materials. |
Patrick Poitras is a student currently wraping up his MSc work, which focused on the use of cascaded SPDC for single photon heralding. |

Zachary Chaisson is an MSc student working using producing polarisation entanglement using cascaded SPDC. |
Alexandre Léger is an MSc student currently working on using active cavities to enhance cascaded SPDC. |

### Past group members

- Micaël Richard (Undergraduate student, 2017, 2019)
- Paul-Henry Glinel (Undergraduate student, 2018)
- Yannick Castonguay-Page (Undergraduate student, 2017)
- Véronique Landry (Undergraduate student, 2016)
- Fallou Kane (MSc student, 2015-2016)

## Publications

An up to date list of publications is available on Google Scholar. All articles are available in open access on arXiv.

- P. Poitras, E. Meyer-Scott & D. R. Hamel, Proposal for low-noise heralded single photons from cascaded downconversion, Optics Express
**26**, 12930 (2018).
- S. Agne, T. Kauten, J. Jin, E. Meyer-Scott, J. Z. Salvail, D. R. Hamel, K. J. Resch, G. Weihs & T. Jennewein, Observation of Genuine Three-Photon Interference, Physical Review Letters
**118**, 53602 (2017).
- L. M. Procopio, L. Rozema, Z. J. Wong, D. R. Hamel, K. O'Brien, X. Zhang, B. Dakic & P. Walther, Single-photon test of hyper-complex quantum theories using a metamaterial, Nature Communications
**8**, 15044 (2017).
- E. Meyer-Scott, D. McCloskey, K. Golos, J. Z. Salvail, K. A. G. Fisher, D. R. Hamel, A. Cabello, K. J. Resch, & T. Jennewein,
*Certifying the Presence of a Photonic Qubit by Splitting It in Two*, Physical Review Letters **116**, 070501, (2016).
- L. K. Shalm et al.
*A strong loophole-free test of local realism*, Physical Review Letters **115**, 250401 (2015).
- L. M Procopio, A. Moqanaki, M. Araújo, F. Costa, I. A Calafell, E. G. Dowd, D. R. Hamel, L. A. Rozema, C. Brukner & P. Walther,
*Experimental superposition of orders of quantum gates*, Nature Communications **6**, 7913 (2015).
- D. R. Hamel, L. K. Shalm, Hübel, A. J. Miller, F. Marsili, V. B. Verma, R. P. Mirin, S. W, Nam, K. J. Resch & T. Jennewein,
*Direct generation of three-photon polarization entanglement*, Nature Photonics **8**, 801-807 (2014).
- P. Kolenderski, C. Scarcella, K. D. Johnsen, D. R. Hamel, C. Holloway, L. K. Shalm, S. Tisa, A. Tosi, K. J. Resch & T. Jennewein,
*Time-resolved double-slit experiment with entangled photons*, Scientific Reports **4**, 4685 (2014).
- L. K. Shalm, D.R. Hamel, Z. Yan, C. Simon, K. J. Resch & T. Jennewein,
*Three-photon energy-time entanglement*, Nature Physics **9**, 19-22 (2013).
- Z. Yan, D. R. Hamel, A. K. Heinrichs, X. Jiang, M. A. Itzler & T. Jennewein,
*An ultra low noise telecom wavelength free running single photon detector using negative feedback avalanche diode*, Review of Scientific Instuments **83**, 073105 (2012).
- R. Prevedel, D.R. Hamel, R. Colbeck, K. Fisher & K.J. Resch,
*Experimental investigation of the uncertainty principle in the presence of quantum memory and its application to witnessing entanglement*, Nature Physics **7**, 757-761 (2011).
- Y. Lu, N. Coish, D.R. Hamel, S. Croke & K.J. Resch,
*Minimum-error discrimination of entangled quantum states*, Physical Review A **82**, 042340 (2010).
- H. Hübel, D.R. Hamel, A. Fedrizzi, S. Ramelow, K.J. Resch & T. Jennewein,
*Direct generation of photon triplets using cascaded photon-pair sources*, Nature **466**, 601-603 (2010).
- D.N. Biggerstaff, R. Kaltenbaek, D.R. Hamel, G. Weihs, T. Rudolph & K.J. Resch,
*Cluster-state quantum computing enhanced by high-fidelity generalized measurements*, Physical Review Letters **103**, 240504 (2009).

## Positions

### Post-doc

Candidates interested in doing a postdoctoral internship in our group can contact me by email with a CV and a summary of research interests.

### Graduate

Positions are available at the MSc and PhD level for motivated students looking to work on projects in quantum optics and quantum information. Those interest should submit an official application for admission to the Université de Moncton, and may also email me in parallel to discuss possible projects. Prospective students are also encouraged to pursue external scholarships, both through UdeM and elsewhere .

### Undergraduate

There are occasionally opportunities for undergraduate students to join the group for summer internships. Interested students are encouraged to contact me by email with their CV and transcript. Spaces are limited, so students are encouraged to get in touch as early as possible. I also encourage students to apply for an NSERC undergraduate research grant . The internal deadline for this competition is usually in early March, it is better to contact in late January at the latest.

## Contact

#### Email

** **

#### Telephone

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#### Address

** Postal **
Université de Moncton
Campus de Moncton
Pavillon Léopold-Taillon
18 avenue Antonine-Maillet
Moncton, NB
Canada E1A 3E9 |
** Physical**
Université de Moncton
Campus de Moncton
Pavillon Rémi-Rossignol
60 rue Notre-Dame-du-Sacré-Coeur
Moncton, NB
Canada |