A list of upcoming possible honors projects can be found below. Take this list as a rough outline only, and approach us if you feel unsure about any of them or if you want to do something different with us.
Fiber based Er laser for trapping individual Rb atoms
A combination of a MOT and an optical tweezer can be used to
efficiently trap
individual neutral atoms. The choice of the wavelength of the optical
tweezer determines how the
internal level structure of the atom is affected by the Stark shift,
and whether
the optical potential created by the light field is truly a "trapping"
potential for
all the states of interest. In this project a diode pumped, fiber based
Erbium
laser will be set up and evaluated for integration into the Rb trapping
experiment.
Consider this project if you have a reasonable atomic physics
background, and fun in building laser systems.
Stabilized interferometer for conditional measurements in quantum
information
One of the possible implementations of quantum computation relies on
the creation of complex entangled states and performing the
computations based on a sequence of measurements. The sucess of these
schemes relies on the ability to create the right states as well as
being able to perform the measurements efficiently. For a multiphoton
based implementation of this concept, measurements on some photons need
to be conditioned on measurement outcomes from other photons in a very
short time (ns). In this project, a currently existing fast switch will
be integrated into a stabilized interferometer to carry out such
measurements as part of a femtosecond parametric down-conversion
experiment.
This project involves design of active stabilization techniques on the
experimental side, and an investigation of accessible information due
to conditional measurements on the slightly more theoretical side.
Rate dependent delay in single photon detectors. Application to
quantum cryptography
Quantum cryptography promises a way to send communicate secretly based on the fundamental laws of physics. In principle, the security of quantum cryptography schemes has been shown, but in practice the theoretical proofs are based on a set of assumptions that might not be fulfilled exactly in practical implementations. This project will look at one particular aspect of practical QKD and will evaluate how it might affect the security of the communication. The response time of photodetectors used in QKD will be characterized with respect to the counting rate and the amount of information leaked to a potential eavesdropper will be analyzed.
Optical nonlinearities in atomic vapours for narrowband photon pair generation
Practical quantum information systems will require the interaction between different physical carriers of quantum information, and the interfacing with photons as the one system most suitable for transport is a must. However, existing photon sources both for single photons and pairs exhibit a too large optical bandwidth for efficient interfacing to atoms and molecules. The aim of this project is to investigate the suitability of the huge optical nonlinearities of an atomic vapor for creating photon pairs with a narrow optical bandwidth, and possibly the setup of such a source.
Minimal quantum state estimation for multiphoton states (=>4)
The process of reconstructing an unknown state from a finite set of measuremets is known as quantum tomography. In a scenario where each copy of the state is part of a limited resource, this reconstruction process should be as efficient as possible. The project will combine building a compactified optical setup and theoretically evaluating optimal detection strategies to bound the estimated state with a minimum number of photons detected. The kit will eventually be used to evaluate the quality of specific 4-photon states produced by parametric down-conversion.
