Connor Kupchak, Philip J. Bustard, Khabat Heshami, Jennifer Erskine, Michael Spanner, Duncan G. England, and Benjamin J. Sussman
Phys. Rev. A 96, 053812 – Published 6 November 2017
The encoding of quantum information in photonic time-bin qubits is apt for long-distance quantum communication schemes. In practice, due to technical constraints such as detector response time, or the speed with which copolarized time-bins can be switched, other encodings, e.g., polarization, are often preferred for operations like state detection. Here, we present the conversion of qubits between polarization and time-bin encodings by using a method that is based on an ultrafast optical Kerr shutter and attain efficiencies of 97% and an average fidelity of 0.827±0.003 with shutter speeds near 1 ps. Our demonstration delineates an essential requirement for the development of hybrid and high-rate optical quantum networks.
Update Jan 2018 – a presentation covering this work was given at the PQE conference, video and slides are available online.
Update August 2017 – this article is now published in PRL, under the alternative title Molecular Frame Reconstruction Using Time-Domain Photoionization Interferometry.
Phys. Rev. Lett. 119, 083401 (2017), DOI: 10.1103/PhysRevLett.119.083401
(Feb 2017) New manuscript on the arxiv:
(Submitted on 29 Jan 2017)
Photoionization of molecular species is, essentially, a multi-path interferometer with both experimentally controllable and intrinsic molecular characteristics. In this work, XUV photoionization of impulsively aligned molecular targets (N2) is used to provide a time-domain route to “complete” photoionization experiments, in which the rotational wavepacket controls the geometric part of the photoionization interferometer. The data obtained is sufficient to determine the magnitudes and phases of the ionization matrix elements for all observed channels, and to reconstruct molecular frame interferograms from lab frame measurements. In principle this methodology provides a time-domain route to complete photoionization experiments, and the molecular frame, which is generally applicable to any molecule (no prerequisites), for all energies and ionization channels.
arxiv 1701.08432 (2017)
Supplementary material (theory, data and code) available at DOI: 10.6084/m9.figshare.4480349.
Feb. 2017 – New article in Chemical Physics Letters:
Kwanghsi Wang(a) , Vincent McKoy(a), Paul Hockett(b), Albert Stolow(b, c, d),Michael S. Schuurman(b, d),
a A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA
b National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
c Department of Physics, University of Ottawa, ON K1N 6N5 Canada
d Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
- • Time-resolved photoelectron angular distributions around conical intersections are studied.
- • Ab initio multiple spawning method is applied to obtain wavepacket densities.
- • Geometry and energy dependent photoelectron matrix elements are employed.
- • Molecular and laboratory photoelectron angular distributions are used to illustrate the non-adiabatic dynamics.
- • Photoelectron spectra are compared with measured values.
We report results from a novel fully ab initio method for simulating the time-resolved photoelectron angular distributions around conical intersections in CS2. The technique employs wavepacket densities obtained with the multiple spawning method in conjunction with geometry- and energy-dependent photoionization matrix elements. The robust agreement of the calculated molecular-frame photoelectron angular distributions with measured values for CS2 demonstrates that this approach can successfully illuminate, and disentangle, the underlying coupled nuclear and electronic dynamics around conical intersections in polyatomic molecules.
UPDATE: Dec. 2017
The figure above has made it as the JCP Christmas card!
The full JCP special issue on Velocity Map Imaging Techniques is also now officially ready, see this page, or this PDF, for all the details.
UPDATE: 4th April 2017
The article is now published in the Journal of Chemical Physics, with an accompanying press release, The Inner Lives of Molecules, from AIP.
The full dataset and analysis scripts are now also available via OSF, DOI: 10.17605/OSF.IO/RRFK3.
Feb. 2017 – new article on the arXiv:
(Submitted on 2 Feb 2017)
The Pixel-Imaging Mass Spectrometry (PImMS) camera allows for 3D charged particle imaging measurements, in which the particle time-of-flight is recorded along with (x,y) position. Coupling the PImMS camera to an ultrafast pump-probe velocity-map imaging spectroscopy apparatus therefore provides a route to time-resolved multi-mass ion imaging, with both high count rates and large dynamic range, thus allowing for rapid measurements of complex photofragmentation dynamics. Furthermore, the use of vacuum ultraviolet wavelengths for the probe pulse allows for an enhanced observation window for the study of excited state molecular dynamics in small polyatomic molecules having relatively high ionization potentials. Herein, preliminary time-resolved multi-mass imaging results from C2F3I photolysis are presented. The experiments utilized femtosecond UV and VUV (160.8~nm and 267~nm) pump and probe laser pulses in order to demonstrate and explore this new time-resolved experimental ion imaging configuration. The data indicates the depth and power of this measurement modality, with a range of photofragments readily observed, and many indications of complex underlying wavepacket dynamics on the excited state(s) prepared.
arXiv 1702.00744 (2017)
Now published in JCP:
The Journal of Chemical Physics 147, 013911 (2017);
Also on Authorea, DOI: 10.22541/au.149030711.19068540
We’ve just finished a manuscript summarising our early work with the Hololens, including data visualization and interdisciplinary work. This is a little different in flavour to our usual work, but will provide a solid foundation for more advanced work with the Hololens, including lab uses and more advanced data visualization.
Paul Hockett & Tim Ingleby
Early hands-on experiences with the Microsoft Hololens augmented/mixed reality device are reported and discussed, with a general aim of exploring basic 3D visualization. A range of usage cases are tested, including data visualization and immersive data spaces, in-situ visualization of 3D models and full scale architectural form visualization. Ultimately, the Hololens is found to provide a remarkable tool for moving from traditional visualization of 3D objects on a 2D screen, to fully experiential 3D visualizations embedded in the real world.
The manuscript is currently available on Authorea, and the arxiv.
Malte C Tichy, Florian Mintert and Andreas Buchleitner
Published 21 September 2011 • 2011 IOP Publishing Ltd
Entanglement is nowadays considered as a key quantity for the understanding of correlations, transport properties and phase transitions in composite quantum systems, and thus receives interest beyond the engineered applications in the focus of quantum information science. We review recent experimental and theoretical progress in the study of quantum correlations under that wider perspective, with an emphasis on rigorous definitions of the entanglement of identical particles, and on entanglement studies in atoms and molecules.
Our recent paper on quantum optical signal processing is now published in Nature Communications:
Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory
Nature Communications 7, 11200, 2016
Kent A.G. Fisher, Duncan G. England, Jean-Philippe W. MacLean, Philip J. Bustard, Kevin J. Resch & Benjamin J. Sussman
The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion.
April 2016 – Article in Nature Communications
Oct. 2015 – Article on the arxiv
New article in the Journal of Modern Optics