M.S. In Physics – Quantum Computing Events

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Molecular Quantum Photonics
Date: Monday, October 24th
Time: 1:30 pm - 2:30 pm
Place: 2401 Chemistry (enter in new North Tower, 2nd floor)
Speaker: Alex S. Clark, Quantum Engineering Technology Labs, University of Bristol
Abstract: Single organic molecules have recently seen increased interest for use as single photon sources [1]. They emit photons with high efficiency and at favourable wavelengths for coupling to other quantum systems, such as alkali atoms [2]. I will present our recent work on growing various mixed molecular crystals [3,4] which show promise for interfacing with rubidium and potassium atoms. I will discuss methods that can be used to tune molecule emission via both applied electric fields and the application of strain [5]. We have recently shown that subsequent photons emitted by a single molecule can undergo quantum interference at a beam splitter [6], which is a useful tool in optical quantum computing and communication. I will discuss how the indistinguishability of photons can not only be ascertained employing pulsed excitation, which is commonly carried out for single quantum emitters, but can also be found via continuous wave excitation as long as measurements are carried out at more than one excitation power. While the excitation of molecules and their subsequent radiative emission is efficient [7], the generated photons can be difficult to collect. There is therefore a large amount of ongoing work on coupling organic molecules to nanophotonic structures to modify their emission. The simplest photonic structure one can imagine is an integrated optical waveguide. I will discuss methods to deposit and evanescently couple molecules to waveguides, and present a hybrid plasmonic structure that has shown recent promise [8]. Evanescent coupling has limitations as the molecules cannot sit at the maximum of the vacuum electric field of the waveguide. I will present our recent work on coupling molecules to interrupted waveguides using on chip micro-capillaries [9]. Finally, I will discuss our future plans to couple molecules to enhance this coupling through the use of nanophotonic cavities.

[1] C. Toninelli et al., Nature Materials 20, 1615-1628 (2021).
[2] P. Siyushev et al., Nature 509, 66-70 (2014).
[3] R. C. Schofield et al., Optical Materials Express 10, 1586-1596 (2020).
[4] R. C. Schofield et al., ChemPhysChem 23, e202100809 (2022).
[5] A. Fasoulakis et al., submitted (2022).
[6] R. C. Schofield et al., Phys. Rev. Research 4, 013037 (2022).
[7] P. Ren et al., Chinese Physics Letters 20, 073602 (2022).
[8] S. Grandi et al., APL Photonics 4, 086101 (2019).
[9] S. Boissier et al., Nature Commun. 12, 706 (2021).
Host: Randall Goldsmith, Chemistry
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