Quantum talks

Find out about our latest quantum talks.

21 November 2019 - Andrew Groszek (Newcastle University) Large Scale Flows in Two-Dimensional Quantum Turbulence.

Non-equilibirum interacting systems can evolve to exhibit large-scale structure and order. In two-dimensional turbulent flow the seemingly random swirling motion of a fluid can evolve towards persistent large-scale vortices. To explain such behaviour, Lars Onsager proposed a statistical hydrodynamic model based on quantised vortices. Our work provides an experimental confirmation of Onsager's model. We drag a grid barrier through an oblate superfluid Bose-Einstein condensate to generate non-equilibrium distributions of quantised vortices. We observe signatures of an inverse energy cascade driven by the "evaporative heating" of these vortices, which leads to steady-state vortex configurations characterised by negative absolute temperatures. We measure these temperatures directly using our recently developed thermometry technique for two-dimensional superfluid turbulence. Complementary observations of negative temperature vortext states have also recently been presented in a similar experiment by Gauthier et al.

7 November 2019 - Dr Rachel Godul (National Physics Laboratory) Optical Atomic Clocks for Testing Fundamental Physics.

For thousands of years, man used the rotation of the Earth as a reference for timekeeping. But the modern world requires far greater precision and the advent of atomic clocks has enabled fractional uncertainties in the realisation of the second to improve by many orders of magnitude. With ever improved accuracy in measurements of time and frequency, it also becomes possible to test fundamental physics at previously inscrutable levels. This talk will present measurements from optical clocks at the National Physics Laboratory that have been used to search for time-variation of fundamental constants and also to place constraints on couplings between Dark Matter and the fields of the Standard Model.

17 October 2019 - Ben Sauer (Imperial College) Direct Laser Cooling of Molecules.

Direct laser cooling techniques that have been developed for atoms can also be applied to certain molecules. Physicists at Imperial College have been workng on cooling of CaF and YbF; diatomic molecules for which quasi-closed transitions can be found. Ben will review the techniques they use and discuss the challenges compared with laser cooling of atoms. He'll discuss their results and in particular how their  laser cooling techniques will enable the next generation of experiments to measure the electron electric dipole moment.

1 August 2019 - Dr Ben Lanyon (University of Innsbruck) Light-matter entanglement over 50km of optical fibre.

When shared between remote locations, entanglement opens up fundamentally new capabilties for science and technology. Envisioned quantum networks use light to distribute entanglement between their remote matter-based quantum nodes. Ben presents his team's observation of entanglement between matter (a trapped ion) and light (a photon) over 50km of optical fibre: two orders of magnitude further than the state of the art and a practical distance to start building large-scale quantum networks.

15 May 2019 - Professor Rainer Blatt (Institute for Experimental Physics, University of Innsbruck) The Quantum Way of Doing Computations.

Rainer will review the basic functional principle of a quantum computer. He'll show how strings of trapped ions can be used to build a quantum information processor and how basic computations can be performed using quantum techniques. The quantum way of doing computations will be illustrated with analog and digital quantum simulations. Ways towards scaling the ion-trap quantum processor will be discussed.

2 April 2019 - Ryan Willets (University of Sussex) Single Microwave Photon Detection.

Ryan will start with an introduction to Penning Traps and move on to describe quantum-non-demolition measurements of multiple single microwave photons. While these measurements have been proven with larger Penning Traps, they have yet to be attempted with a scalable Penning Trap.

26 March 2019 - Tim James (University of Sussex) The two colour magneto optical trap.

Tim will explore how a second cooling frequency can improve the number of atoms trapped in a magneto-optical trap (MOT). He'll explain what a "two colour" MOT is and how it differs from the "single colour" MOT. Using experimental results, he'll cover some basic theoretical ideas around the two colour MOT.

5 March 2019 - Juan Sebastian Totero Gongero (University of Sussex) Complexity-driven photonics.

Juan will introduce some of the concepts underlying the field of complexity-driven photonics. He'll discuss how in the laboratory they are employing the "spontaneous synchronisation" of interacting optical waves to design ultrafast pulsed lasers, quantum information sources and brain-inspired optical computing devices.

26 February 2019 - Seokjun Hong (University of Sussex) Microfabrication of Surface Ion Trap Chips.

Seokjun will start with a brief introduction of qubit platform and the history of ion trap structures. He will move on to focus on the detailed microfabrication processes required for advanced surface ion traps.

5 February 2019 - Harry Bostock (University of Sussex) Quantum Sensing using Trapped Ions.

Much has been seen of trapped ions as a method for quantum computing, but one exciting new application for this technology is using them for radio frequency, microwave, and static field sensing. Harry will show how trapped ions can be used as quantum sensors and how they have the potential to outclass both well-established classical sensors and other quantum sensors.