AtMol Research Seminar Archive
Index Current Seminars

Epiphany 2010

Date Speaker Institution
First year talk: Towards RbCs ground state molecules
19th January Michael Köppinger Durham university

First year phD students in the Atomic and molecular group (that are around 9 months into their research), are required to give a 40 minute seminar on their work so far.

Journal club talk: Stable Optical Lift
26th January Mr James Keaveney Durham University

Aerodynamic lift, in which a cambered object (an aerofoil) experiences a transverse lift force when in relative motion with air, is a familiar idea. This talk presents results from a recent paper, in which an optical equivalent of aerodynamic lift is predicted and observed in micrometer-scale objects under uniform illumination. A semi-cylindrical rod is found to automatically torque into a stable angle-of-attack, then then exhibit uniform motion. The authors propose that these devices can be used to improve the design of solar sails, for long range space travel.

No Seminar
2nd February

Journal club talk: Random numbers certified by Bell's theorem
9th February Mr Tim Wiles Durham University

The ability to generate random numbers is incredibly useful for a wide range of differing fields, such as Monte Carlo simulations and cryptography. Generating truly random numbers is difficult and requires an unpredictable process which can be exploited. Within classical mechanics a system only appears random until the processes behind it are understood. The intrinsic random nature of quantum mechanics can solve this problem. The paper presented in this talk will cover the quantum mechanical generation of 42 new random numbers, in a system with two entangled atoms, which are confirmed to be random by a Bell inequality violation.

Molecules at Millikelvin and Below
16th February Prof. Jeremy Hutson Durham University

Prof. Jeremy Hutson is presenting his work in ultracold chemistry at 16:15 in CG60 (department of chemistry) rather than Ph8. This will effectively replace the atmol seminar for the week. The abstract is below.

It is now possible to form molecules at extremely low temperatures, where all molecular motions including translation are fully quantum-mechanical. This capability opens up new possibilities for precision measurement and quantum control of molecular systems, with potential applications in quantum computing and elsewhere. However, at present the capability is limited to one or two molecular systems. This talk will describe how ultracold molecules are formed and explore some of their novel properties.

Schrödinger’s Bath Plug
(Monday) 21st Febuary Prof. Keith Burnett (VC) University of Sheffield

I will discuss studies of rotating assemblies of cold atoms in the pursuit of multi-particle superposition states. We can think of this as trying to produce the neutral atom version of a SQUID. The states involved can also be considered in terms of strongly correlated or entangled assemblies of atoms. I will show how this work links to that on quantum nucleation of vortices and the production of the Bosonic analogue of fractional quantum hall states.

Engineering Near-Circular High-n Wave Packets
23rd February Prof. F. Barry Dunning Rice University, Houston, Texas

Atoms in high-n (n>300) Rydberg states provide an opportunity to engineer electronic wave functions using carefully-tailored sequences of short electric field pulses whose characteristic times (duration and/or rise/fall times) are less than the classical Kepler period, ~4.3 ns at n~300. The level of control that can be achieved is illustrated by reference to protocols developed to create localized wave packets that move in near-circular Bohr-like orbits, to search for quantum effects in high-n atoms, and to examine information storage/retrieval and dephasing/decoherence in Rydberg states. The physical processes underlying the various protocols are discussed using classical trajectory Monte Carlo simulations.

Coherent control of highly excited Rydberg states
2nd March Dr. Robert Loew University of Stuttgart

In this talk I will present results on the coherent control of a strongly interacting Rydberg gas and ultralong range Rydberg molecules at ultracold temperatures. The method of choice is Ramsey interferometry, which allows to distinguish decoherence due to radiative decay and energy conserving dephasing. In the second part, I will present the coherent dynamic in thermal vapors involving Rydberg states, when driven with intense laser pulses.

Journal club talk: Detection of Hawking radiation from an optical analogue to a black hole.
9th March Mr Daniel Maxwell Durham University

In 1974 Stephen Hawking proposed that black holes are not completely black and should emit thermal radiation with a black body spectrum (Hawking radiation). However its very low temperature in addition to the fact that black holes are extremely distant from the earth makes the direct detection of Hawking radiation unfeasible. In this talk I will discuss physical systems which can be implemented in the laboratory which display some of the important features of black holes. In particular the talk will focus on a recent paper entitled “Hawking radiation from ultrashort laser pulse filaments”  (Phys. Rev. Lett. 105, 203901) in which the researchers claim to have observed Hawking radiation for the first time.

Modelling quasi-1D Bose gases with the stochastic Gross-Pitaevskii equation (room ph30)
16th March Dr Stuart Cockburn Newcastle University

The theoretical description of weakly interacting, highly elongated Bose gases represents an interesting challenge, due to the enhanced role played by phase and density fluctuations within quasi-one-dimensional geometries. This talk will focus on the stochastic Gross-Pitaevskii equation (SGPE) as a model for such systems, comparing numerical results to equilibrium data from both experiments and other theoretical methods. As an application of the SGPE to a non-equilibrium system, we will also discuss the dynamics of dark solitons within phase fluctuating condensates.

Perspectives on itinerant ferromagnetism in an atomic Fermi gas
30th March Dr Gareth.J. Conduit University of Cambridge

The Ketterle group at MIT has recently provided the first tentative evidence for the formation of an itinerant ferromagnetic state in a ultracold gas of Fermions with repusive interactions. Here we first review the evidence for the formation of a ferromagnetic phase and study the competing instabilities. Secondly, we look ahead to possible new experimental protocols for the next generation of the experiment.

Non-Equilibrium Dynamics of a Many-Body Quantum System
(Thursday) 7th April Dr. David A. Smith Vienna University of Technology

The study of non-equilibrium dynamics in many-body quantum systems is at the forefront of theoretical research across a wide range of research topics. However, the number of experimental systems available for detailed study are few in number. In this seminar, the results of a new experiment investigating such a system will be discussed. Making use of the controllability and accessibility of ultracold atoms, we have created a non-equilibrium system that we study using full distribution functions (FDFs), going beyond the measurement of mean values and showing unequivocally the multi-mode nature of 1d Bose gases. The FDFs also expose two distinct regimes related to length scales within the system, showing correlations on a much greater length scale than that expected from the thermal phase correlation length.

Too be announced
(Monday) 11th April As. Prof. Dr. Thorsten Schumm Vienna University of Technology

Room Bookings for Ph30 are made by contacting Ian Buckingham at Student Planning and Assessment by internal phone number: 46430
This can be viewed online at: http://timetable.dur.ac.uk/room_dur.htm
Select Room: D/PH30 (106)
Room is currently booked for weeks: 10-19, 25-33, 39-47.