THz-bandwidth all-optical switching of heralded single photons

THz-bandwidth all-optical switching of heralded single photons

Update March 2019 – now in Optics Letters, DOI: 10.1364/OL.44.001427

June 2018 – New on arXiv.

Optically induced ultrafast switching of single photons is demonstrated by rotating the photon polarization via the Kerr effect in a commercially available single mode fiber. A switching efficiency of 97\% is achieved with a 1.7\,ps switching time, and signal-to-noise ratio of 800. Preservation of the quantum state is confirmed by measuring no significant increase in the second-order autocorrelation function g(2)(0). These values are attained with only nanojoule level pump energies that are produced by a laser oscillator with 80\,MHz repetition rate. The results highlight a simple switching device capable of both high-bandwidth operations and preservation of single-photon properties for applications in photonic quantum processing and ultrafast time-gating or switching.

Quantum Canada

Quantum Canada

Feb 2019: New article in Quantum Science and Technology

Canada ranks among the world’s leading nations in quantum research, building on investments of more than $1 billion in the past decade alone. Canada’s amassed research expertise, growing private-sector impact, and government commitments to innovation and competitiveness, place the country in a strong position, as scientific advances drive quantum technology development. Here, we summarize the steps Canada has taken to build quantum research excellence and to support a growing quantum industrial base. We also discuss Canadian quantum community efforts to solidify and build the nation’s leadership, as the technology revolution unfolds.

Ben SussmanPaul CorkumAlexandre BlaisDavid Cory and Andrea Damascelli

2019 Quantum Sci. Technol. 4 020503

DOI: 10.1088/2058-9565/ab029d

Quantum Beat Photoelectron Imaging Spectroscopy of Xe in the VUV

Quantum Beat Photoelectron Imaging Spectroscopy of Xe in the VUV

UPDATE June 2018 – Now published in Phys. Rev. A 97, 063417, 2018, DOI: 10.1103/PhysRevA.97.063417

… and in Kaleidoscope.

March 2018: New on arXiv

Time-resolved pump-probe measurements of Xe, pumped at 133~nm and probed at 266~nm, are presented. The pump pulse prepared a long-lived hyperfine wavepacket, in the Xe 5p5(2P1/2)6s 2[1/2]1 manifold (E=77185 cm1=9.57 eV). The wavepacket was monitored via single-photon ionization, and photoelectron images measured. The images provide angle- and time-resolved data which, when obtained over a large time-window (900~ps), constitute a precision quantum beat spectroscopy measurement of the hyperfine state splittings. Additionally, analysis of the full photoelectron image stack provides a quantum beat imaging modality, in which the Fourier components of the photoelectron images correlated with specific beat components can be obtained. This may also permit the extraction of isotope-resolved photoelectron images in the frequency domain, in cases where nuclear spins (hence beat components) can be uniquely assigned to specific isotopes (as herein), and also provides phase information. The information content of both raw, and inverted, image stacks is investigated, suggesting the utility of the Fourier analysis methodology in cases where images cannot be inverted.

Also available on Authorea.

Full data, code & analysis notes on OSF.

Time-bin-to-polarization conversion of ultrafast photonic qubits

Time-bin-to-polarization conversion of ultrafast photonic qubits

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.

Bootstrapping to the Molecular Frame with Time-domain Photoionization Interferometry

Bootstrapping to the Molecular Frame with Time-domain Photoionization Interferometry

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:

Bootstrapping to the Molecular Frame with Time-domain Photoionization Interferometry


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.

Angle-resolved RABBIT: theory and numerics

Angle-resolved RABBIT: theory and numerics

Update 28/06/17 – Now published in J. Phys. B, special issue on Correlations in Light-Matter Interactions.

New manuscript:

Angle-resolved RABBIT: theory and numerics

P. Hockett

Angle-resolved (AR) RABBIT measurements offer a high information content measurement scheme, due to the presence of multiple, interfering, ionization channels combined with a phase-sensitive observable in the form of angle and time-resolved photoelectron interferograms. In order to explore the characteristics and potentials of AR-RABBIT, a perturbative 2-photon model is developed; based on this model, example AR-RABBIT results are computed for model and real systems, for a range of RABBIT schemes. These results indicate some of the phenomena to be expected in AR-RABBIT measurements, and suggest various applications of the technique in photoionization metrology.

Paul Hockett 2017 J. Phys. B: At. Mol. Opt. Phys. 50 154002

Pre-print available via Authorea, DOI: 10.22541/au.149037518.89916908.

arXiv 1703.08586 (2017) 

See also the recent AR-RABBIT presentation for a brief intro to this topic.

Open Science Initiative

Open Science Initiative

Open science – the practice of making full research projects open and accessible, from inception to publication – is an increasingly important topic, and even appearing in the popular press, particularly with regard to transparency and reproducible in research… hence open science can be viewed as the opposite of bad science.

John Arnold Made a Fortune at Enron. Now He’s Declared War on Bad Science

Open science (along with the more general notion of open data) is also part of the Canadian Government’s Open Government action plan, which includes the statement that:

The Government of Canada will maximize access to federally-funded scientific research to encourage greater collaboration and engagement with the scientific community, the private sector, and the public.


As part of our work towards open science, our articles are increasingly available on open platforms (arXiv, Authorea). And, now, good things are happening with our data too. Thanks to the Open Science Foundation (OSF) and Figshare, it’s now easy to share data, code etc. and make it citable with a DOI.

Some of our recent open science data can be found at:

Time-dependent Wavepackets and Photoionization – CS2 (2013 – present)

Our ongoing work on the calculation of time-dependent wavepackets and observables in photoionization is now collected in an OSF project (DOI: 10.17605/OSF.IO/RJMPD). Aspects of this work have previously been published, but much of the detail and methodology underlying the calculations has remained sitting on our computers. As part of our Open Science Initiative, we’re letting this data go free! Head over to the OSF project “Time-dependent Wavepackets and Photoionization – CS2” for more.

Photoionization dynamics – collected results from ePolyScat (ongoing)

An OSF project, collecting photoionization calculations (ePolyScat), and notes, is now available. This will be an ongoing resource for researchers in photoelectron spectroscopy, interferometry and related areas, and is part of our Open Science initiative.

Quantum Beat Photoelectron Imaging Spectroscopy of Xe in the VUV (2018)

Time-resolved multi-mass ion imaging: femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera (2017)

Bootstrapping to the Molecular Frame with Time-domain Photoionization Interferometry (2017)

Time Delay in Molecular Photoionization (2016)

Let your data be free!

Monitoring Non-adiabatic Dynamics in CS2 with Time- and Energy-Resolved Photoelectron Spectra of Wavepackets

Monitoring Non-adiabatic Dynamics in CS2 with Time- and Energy-Resolved Photoelectron Spectra of Wavepackets

Feb. 2017 – New article in Chemical Physics Letters:

Monitoring Non-adiabatic Dynamics in CS2 with Time- and Energy-Resolved Photoelectron Spectra of Wavepackets

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.

DOI: 10.1016/j.cplett.2017.02.014