Fibre VUV generation & applications

Fibre VUV generation & applications

Over the last few months (summer 2018) a new project has been shaping up, in collaboration with colleagues from the PCF division (Russell research group) at MPL.  The aim is to develop new ultrafast experiments based on their hollow-core PCFs, which can be used to provide tuneable UV and VUV. This work is part of our larger source development project, and will develop towards applications in photoelectron metrology and quantum optics (amongst others!).

More details to follow, but for now here are a few images of the work in progress…

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.

THz-bandwidth all-optical switching of heralded single photons

THz-bandwidth all-optical switching of heralded single photons

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.

Reading today…

Reading today…

Remote quantum entanglement between two micromechanical oscillators

Ralf RiedingerAndreas WallucksIgor MarinkovićClemens LöschnauerMarkus AspelmeyerSungkun Hong & Simon Gröblacher

Nature volume 556pages 473–477 (2018)

Entanglement, an essential feature of quantum theory that allows for inseparable quantum correlations to be shared between distant parties, is a crucial resource for quantum networks1. Of particular importance is the ability to distribute entanglement between remote objects that can also serve as quantum memories. This has been previously realized using systems such as warm2,3 and cold atomic vapours4,5, individual atoms6 and ions7,8, and defects in solid-state systems9,10,11. Practical communication applications require a combination of several advantageous features, such as a particular operating wavelength, high bandwidth and long memory lifetimes. Here we introduce a purely micromachined solid-state platform in the form of chip-based optomechanical resonators made of nanostructured silicon beams. We create and demonstrate entanglement between two micromechanical oscillators across two chips that are separated by 20 centimetres . The entangled quantum state is distributed by an optical field at a designed wavelength near 1,550 nanometres. Therefore, our system can be directly incorporated in a realistic fibre-optic quantum network operating in the conventional optical telecommunication band. Our results are an important step towards the development of large-area quantum networks based on silicon photonics.

(Image above from the related Science news item, Einstein’s ‘spooky action at a distance’ spotted in objects almost big enough to see.)

Reading today…

Reading today…

Relativistic and QED Effects in the Fundamental Vibration of T2

T. Madhu Trivikram, M. Schlösser, W. Ubachs, and E. J. Salumbides

Phys. Rev. Lett. 120, 163002 – Published 16 April 2018

The hydrogen molecule has become a test ground for quantum electrodynamical calculations in molecules. Expanding beyond studies on stable hydrogenic species to the heavier radioactive tritium-bearing molecules, we report on a measurement of the fundamental T2 vibrational splitting (v=01) for J=05 rotational levels. Precision frequency metrology is performed with high-resolution coherent anti-Stokes Raman spectroscopy at an experimental uncertainty of 10–12 MHz, where sub-Doppler saturation features are exploited for the strongest transition. The achieved accuracy corresponds to a 50-fold improvement over a previous measurement, and it allows for the extraction of relativistic and QED contributions to T2 transition energies.

Reading today…

Reading today…

Building one molecule from a reservoir of two atoms

L. R. Liu, J. D. Hood, Y. Yu, J. T. Zhang, N. R. Hutzler, T. Rosenband, K.-K. Ni

Science 12 Apr 2018: eaar7797, DOI: 10.1126/science.aar7797

Chemical reactions typically proceed via stochastic encounters between reactants. Going beyond this paradigm, we combine exactly two atoms into a single, controlled reaction. The experimental apparatus traps two individual laser-cooled atoms (one sodium and one cesium) in separate optical tweezers and then merges them into one optical dipole trap. Subsequently, photo-association forms an excited-state NaCs molecule. The discovery of previously unseen resonances near the molecular dissociation threshold and measurement of collision rates are enabled by the tightly trapped ultracold sample of atoms. As laser-cooling and trapping capabilities are extended to more elements, the technique will enable the study of more diverse, and eventually more complex, molecules in an isolated environment, as well as synthesis of designer molecules for qubits.

Quantum Metrology with Photoelectrons (book)

Quantum Metrology with Photoelectrons (book)

Update April 2018 – the books are now available via IOP, see details at end of post.

Book for IOP Concise Physics series, due early 2018

Dr. Paul Hockett

National Research Council of Canada

Online resources

OSF project (ID: q2v3g) with interactive content and additional resources, DOI: 10.17605/OSF.IO/Q2V3G

femtolab.ca website, posts tagged “metrology-book”

femtolab.ca website, posts tagged “video”

Abstract

Photoionization is an interferometric process, in which multiple paths can contribute to the final continuum photoelectron wavefunction. 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. In these cases, the continuum wavefunction (and underlying scattering dynamics) can be characterised. At a more complex level, such measurements can also provide a powerful probe for other processes of interest, leading to a more general class of quantum metrology built on phase-sensitive photoelectron imaging.  Since the turn of the century, the increasing availability of photoelectron imaging experiments, along with the increasing sophistication of experimental techniques, and the availability of computational resources for analysis and numerics, has allowed for significant developments in such photoelectron metrology.

Volume I covers the core physics of photoionization, including a range of computational examples. The material is presented as both reference and tutorial, and should appeal to readers of all levels.  Volume II explores applications, and the development of quantum metrology schemes based on photoelectron measurements. The material is more technical, and will appeal more to the specialist reader.

Full text

Quantum Metrology with Photoelectrons

Volume 1
ISBN 978-1-6817-4684-5
http://iopscience.iop.org/book/978-1-6817-4684-5
Volume 2
ISBN 978-1-6817-4688-3
http://iopscience.iop.org/book/978-1-6817-4688-3