Positions Vacant!
Our group is seeking PhD students to work on the following projects:
* Quantum Communication
* Quantum Information
* Quantum Cryptography
* Quantum Memory
* Atom-Light Entanglement
Specific Honour Projects for 2008
Contact: ping.lam@anu.edu.au
Harmonic Entanglement
Experiment + Theory
Conventionally optical entanglement is produced using nonlinear optical processes, such as optical parametric oscillation and amplification. The twin beams generated by these processes usual have similar wavelength. The aim of this honours project is to be the first in the world to observe entanglement between a light beam and its second harmonic. This type of "Harmonic Entanglement" provides a means to entangle light of different color (wavelength). In our experiment, an infra-red beam will be entangled with a green light beam.
Harmonic entanglement is a type of interspecies entanglement useful for quantum information protocols. It has the potential to enable quantum communication between different systems. Our group was the first to show theoretically that harmonic entanglement can be generated between the fundamental and the second harmonic fields of a suitably pumped second order nonlinear system [Phys. Rev. Lett. 96, 063601 (2006)].
Photon-Field Quantum Optics
Quantum Optics Research Group
Experiment + Theory
It is often said that quantum mechanics will revolutionize 21st century technologies in the same way as the electromagnetic theory did in the 20th century. Potential application of quantum mechanics range from sensing, communication, to the realization of quantum computers. Central to many of these application is the requirement of quantum entanglement. Entanglement, can be thought of as a physical resource associated with the peculiar non-classical "connection" established between separated systems.
This honours project aims further the understanding of the properties of entanglement in relations to two methods of optical detections. On one hand, light could be considered as corpuscular where photon counters can detect photon arrival statistics. On the other hand, light could be considered as wave where PIN photodiodes in a homodyne setup can measure optical field fluctuations. By considering a “hybridised” experiment that uses nonlinear optical processes to generate quantum entanglement, the program aims to exploit the merits of measuring both photon and field properties of light in an integrated experiment. Experiments with photon-field detection potentially have greater versatility in providing a mean to engineer useful quantum states for quantum information applications such as the realization of quantum repeaters for quantum tele-communication systems and networks.
Continuous Variable Quantum Cryptography
Quantum Optics Research Group
Experiment + Theory
Cryptography is in widespread commercial use today, as is exemplified by the ubiquity of the little padlock icons on internet browsers. Currently, RSA encryption protocols lies at the heart of many crypto-systems deployed to secure communication. The security of these of cryptographic systems relies on computational complexity. That is to say, it is secure only because it is computationally very challenging to break the code. These encryption systems are therefore not absolutely secure and are potentially vulnerable with the advent of advanced algorithms or quantum computation.
Quantum physics offers a solution to the problem of achieving absolute information security. In quantum cryptography, information security is guaranteed by the laws of physics when communication is established via the transmission of many fragile quantum optical states. An eavesdropper's presence always results in collapsing the quantum wave-function of the transmitted state and is thus easily detected.
Quantum cryptography is a direct application of quantum physics for the realization of a 'real world' application. It has the potential to re-define the way information security is delivered in today's information intensive world. The ANU team is working on a practical quantum cryptography system based on bright beam techniques (continuous variable). Further information can be obtained from the following published work:
[Phys. Rev. Lett. 93, 170504 (2004)]
[Phys. Rev. Lett. 95, 180503 (2005)]
ANU Quantum Optics
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