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.
New article in Optics Letters.
Jennifer Erskine, Duncan England, Connor Kupchak, and Benjamin Sussman
Optics Letters Vol. 43, Issue 4, pp. 907-910 (2018)
Photon pair sources have wide ranging applications in a variety of quantum photonic experiments and protocols. Many of these protocols require well controlled spectral correlations between the two output photons. However, due to low cross-sections, measuring the joint spectral properties of photon pair sources has historically been a challenging and time-consuming task. Here, we present an approach for the real-time measurement of the joint spectral properties of a fiber-based four wave mixing source. We seed the four wave mixing process using a broadband chirped pulse, studying the stimulated process to extract information regarding the spontaneous process. In addition, we compare stimulated emission measurements with the spontaneous process to confirm the technique’s validity. Joint spectral measurements have taken many hours historically and several minutes with recent techniques. Here, measurements have been demonstrated in 5–30 s depending on resolution, offering substantial improvement. Additional benefits of this approach include flexible resolution, large measurement bandwidth, and reduced experimental overhead.
The gas-phase structures of four difluoroiodobenzene and two dihydroxybromobenzene isomers were identified by correlating the emission angles of atomic fragment ions created, following femtosecond laser-induced Coulomb explosion. The structural determinations were facilitated by confining the most polarizable axis of each molecule to the detection plane prior to the Coulomb explosion event using one-dimensional laser-induced adiabatic alignment. For a molecular target consisting of two difluoroiodobenzene isomers, each constituent structure could additionally be singled out and distinguished.
Talk originally given as a 20min presentation at PQE 2018 (Snowbird, Utah, http://pqeconference.com/pqe2018/program). The original talk was not recorded; this is an extended version using the same slides, but with rather more introductory discussion. The abstract is given below, along with links to additional material.
More details of the work discussed in the main part of the talk can be found in:
Molecular Frame Reconstruction Using Time-Domain Photoionization Interferometry.
Marceau et. al., Physical Review Letters, 119(8), 83401 (2017).
- arXiv 1701.08432 (https://arxiv.org/abs/1701.08432).
- Full docs, data & code repository: https://dx.doi.org/10.6084/m9.figshare.4480349
- Slides: https://doi.org/10.6084/m9.figshare.5645509
- For further info on the upcoming book Quantum Metrology with Photoelectrons: https://osf.io/q2v3g/
- For those curious about the term bootstrapping, see Wikipedia
PQE 2018 Abstract
Bootstrapping (Ultrafast) Photoionization Dynamics
Slot: Tuesday Morning Invited Session 1
Session: Ultrafast photoionization dynamics
Photoionization is an interferometric process, in which multiple paths can contribute to the final continuum photoelectron state. At the simplest level, interferences between different final angular momentum states are clearly manifest in the energy and angle resolved photoelectron spectra; metrology schemes making use of these interferograms are thus phase-sensitive, and provide a powerful route to detailed understanding of photoionization.
The high information content of angle-resolved interferograms, combined with geometric control over the photoionization dynamics, can provide sufficient data for reconstruction of the continuum state, in terms of the constituent partial waves and phases. This has recently been explored for a range of cases, including the use of ultrafast pump-probe schemes with a bootstrapping analysis methodology: aspects of this work will be presented.
Molecular Frame Reconstruction Using Time-Domain Photoionization Interferometry
Marceau, C., Makhija, V., Platzer, D., Naumov, A. Y., Corkum, P. B., Stolow, A., Villeneuve, D. M., Hockett, P. (2017). Physical Review Letters, 119(8), 83401. http://doi.org/10.1103/PhysRevLett.119.083401
Coherent control of photoelectron wavepacket angular interferograms.
Hockett, P., Wollenhaupt, M., & Baumert, T. (2015). Journal of Physics B: Atomic, Molecular and Optical Physics, 48(21), 214004. http://doi.org/10.1088/0953-4075/48/21/214004
Complete Photoionization Experiments via Ultrafast Coherent Control with Polarization Multiplexing.
Hockett, P., Wollenhaupt, M., Lux, C., & Baumert, T. (2014). Physical Review Letters, 112(22), 223001. http://doi.org/10.1103/PhysRevLett.112.223001
Coherent imaging of an attosecond electron wave packet.
Villeneuve, D. M., Hockett, P., Vrakking, M. J. J., & Niikura, H. (2017). Science, 356(6343), 1150–1153. http://doi.org/10.1126/science.aam8393
Rev. Mod. Phys. 88, 015007 – Published 9 March 2016
A new scientific frontier opened in 2009 with the start of operations of the world’s first x-ray free-electron laser (FEL), the Linac Coherent Light Source (LCLS), at SLAC National Accelerator Laboratory. LCLS provides femtosecond pulses of x rays (270 eV to 11.2 keV) with very high peak brightness to access new domains of ultrafast x-ray science. This article presents the fundamental FEL physics and outlines the LCLS source characteristics along with the experimental challenges, strategies, and instrumentation that accompany this novel type of x-ray source. The main part of the article reviews the scientific achievements since the inception of LCLS in the five primary areas it serves: atomic, molecular, and optical physics; condensed matter physics; matter in extreme conditions; chemistry and soft matter, and biology.
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.
Example of new detector mounting in our VIRP chamber, as part of our work testing ion detection technologies. The image shows a Mega-Spiraltron detector for high-pressure (up to 10^-3 mbar) charged particle detection.
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:
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.
Supplementary material (theory, data and code) available at DOI: 10.6084/m9.figshare.4480349.