Phase-sensitive Photoelectron Metrology (presentation at DAMOP 2017)

Phase-sensitive Photoelectron Metrology (presentation at DAMOP 2017)

Slides for Paul’s DAMOP talk are now available on figshare (DOI: 10.6084/m9.figshare.5049142).

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 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 [1]. At a more complex level, such measurements can also provide a powerful probe for other processes of interest, for example: (a) dynamical process in time-resolved measurements, such as rotational, vibrational and electronic wavepackets, and (b) in order to understand and develop control schemes [1]. In this talk recent work in this vein will be discussed, touching on “complete” photoionization studies of atoms and molecules with shaped laser pulses [1,2] and XUV [3], metrology schemes using Angle-Resolved RABBIT, and molecular photoionization dynamics in the time-domain (Wigner delays) [4].

[1] Hockett, P. et. al. (2015). Phys. Rev. A, 92, 13412. [2] Hockett, P. et. al. (2014). Phys. Rev. Lett., 112, 223001. [3] Marceau, C. et. al. (2017). Submitted. DOI: 10.6084/m9.figshare.4480349. [4] Hockett, P. et. al. (2016). J. Phys B, 49, 95602.

Update 29th June 2017 – a video of the talk is now also available.

Phase-sensitive Photoelectron Metrology – Dr. P. Hockett, presentation at DAMOP 2017 from femtolab.ca on Vimeo.

Time-dependent Wavepackets and Photoionization – CS2

Time-dependent Wavepackets and Photoionization – CS2

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.

Figure shows TRPADs results (a) Calculated TRPADs (0.7eV) (b), (c) Comparison with expt. TRPADs (discrete times).

Reading today…

Reading today…

Nonlinear quantum optics mediated by Rydberg interactions

O Firstenberg, C S Adams and S Hofferberth

Published 30 June 2016© 2016 IOP Publishing Ltd
Journal of Physics B: Atomic, Molecular and Optical Physics, Volume 49, Number 15
Special Issue on Rydberg Atomic Physics

By mapping the strong interaction between Rydberg excitations in ultra-cold atomic ensembles onto single photons via electromagnetically induced transparency, it is now possible to realize a medium which exhibits a strong optical nonlinearity at the level of individual photons. We review the theoretical concepts and the experimental state-of-the-art of this exciting new field, and discuss first applications in the field of all-optical quantum information processing.

DOI: 10.1088/0953-4075/49/15/152003

Fascinating insight into the topic, which utilises the properties of Rydberg matter to enable traditional non-linear optics to cross over to the quantum regime. From the intro:

One remarkable success of advances in ultra-cold Rydberg physics is the realization of a medium with a large optical nonlinearity at the single photon level [1–3]. Highly excited Rydberg atoms bring something new to the history of optics as they enable quantum nonlinear media where photons are strongly interacting!

Recommended.

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.

Angle-resolved RABBIT: new work and presentation

Angle-resolved RABBIT: new work and presentation

The above image shows simulated velocity map images (left, middle) and angle and time-resolved measurements (right) for angle-resolved RABBIT measurements. In this type of measurement, XUV and IR pulses are combined, and create a set of 1 and 2-photon bands in the photoelectron spectrum. The presence of multiple interfering pathways to each final photoelectron band (energy) results in complex and information rich interferograms, with both angle and time-dependence.

A manuscript detailing this work is currently in preparation, and a recent presentation detailing some aspects of the work can be found on Figshare.

Update 24th March – new manuscript, Angle-resolved RABBIT: theory and numerics, pre-print available.

Reading today…

Reading today…

First On-Sky Fringes with an Up-Conversion Interferometer Tested on a Telescope Array

P. Darré, R. Baudoin, J.-T. Gomes, N. J. Scott, L. Delage, L. Grossard, J. Sturmann, C. Farrington, F. Reynaud, and T. A. Ten Brummelaar
Phys. Rev. Lett. 117, 233902 – Published 29 November 2016

10.1103/PhysRevLett.117.233902

The Astronomical Light Optical Hybrid Analysis project investigates the combined use of a telescope array interferometer and nonlinear optics to propose a new generation of instruments dedicated to high-resolution imaging for infrared astronomy. The nonlinear process of optical frequency conversion transfers the astronomical light to a shorter wavelength domain. Here, we report on the first fringes obtained on the sky with the prototype operated at 1.55μm in the astronomical H band and implemented on the Center for High Angular Resolution Astronomy telescope array. This seminal result allows us to foresee a future extension to the challenging midinfrared spectral domain.

This is quite interesting as an application of photon up-conversion at low-light levels – in this case for interferometric IR telescope arrays.  The demo in the paper doesn’t show any improvement on the existing configuration (i.e. no non-linear optical step), but in principle could: once one factors in not just lossy detection in the IR, but also lossy beam transport (in the conceptually similar VLTI system it’s about 10% efficient).

The header image shows fig. 1 from the paper.

Reading today…

Reading today…

Essential entanglement for atomic and molecular physics

Malte C Tichy, Florian Mintert and Andreas Buchleitner

Published 21 September 20112011 IOP Publishing Ltd
Journal of Physics B: Atomic, Molecular and Optical Physics, Volume 44, Number 19

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.

Coherent quantum control & metrology

Coherent quantum control & metrology

UPDATE March 2016 – The article has been chosen for the JPB Highlights of 2015 selection, which features articles selected for their “outstanding quality and impact within the field”. The articles in the collection will be open access for the year.

Our recent paper on coherent control & quantum metrology is now published in J. Phys. B:

Coherent control of photoelectron wavepacket angular interferograms
P Hockett, M Wollenhaupt and T Baumert
J. Phys. B: At. Mol. Opt. Phys. 48 (2015) 214004.
doi: 10.1088/0953-4075/48/21/214004

Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light–matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable.

The work is part of the special issue on Coherence and Control in the Quantum World.

The manuscript is also available on the arxiv.

UPDATE Nov. 2015 – Chosen for the cover of the 14th November 2015 print edition.

JPB cover

Quantum scattering in NO2 (pt II)

Quantum scattering in NO2 (pt II)

Another brief glimpse at some recent work – scattering calculations for NO2 (pt II – see pt I here)…

no2 orb 12 ionization

 

(top) the molecular-frame photoelectron flux for light-matter interaction for various photon energies (hence various electron energies) for linearly polarized light aligned to the plane of the molecule.

(middle & bottom) the magnitudes & phases of the various partial wave components which make up the continuum electron wavefunction.  There is a lot of information here!

This is just a snippet from an ongoing effort to explore quantum coherence in molecular ionization.

Quantum scattering in NO2

Quantum scattering in NO2

A brief glimpse at some recent work – scattering calculations for NO2.  The figure shows the molecular-frame photoelectron flux for light-matter interaction of various geometries (linearly polarized light), hence scattering into different continua.  The inset shows the ionizing orbital and molecular geometry.

This is just a snippet from an ongoing effort to explore quantum coherence in molecular ionization.