University of Waterloo
200 University Avenue West
Waterloo, Ontario, Canada N2L 3G1
Phone: (519) 888-4567 ext 32215
Fax: (519) 746-8115
Dr. Kycia's group works on the experimental investigation of superconducting and quantum mechanical devices; in particular Superconducting Quantum Interference Devices (SQUIDs), Transition Edge Sensors (TESs) Kinetic Inductance Detectors (KIDs), GaAs quantum dots (Spin Qubits). We run our experiments at ultra low temperatures (down to 0.004K). We work on applying these devices for quantum computing, for state of the art telescope detectors, and for studying novel magnetic and superconducting materials.
Systems of interacting magnetic moments have long been used by physicists as a basis for studying and testing numerous models in statistical physics. Magnetic systems may often possess a well-defined Hamiltonian to use as a starting point for understanding the nonetheless very complex behaviour that may result. One of the most difficult of such models to study theoretically is the effect of disorder which may be caused by random interactions between spins or by a random dilution of the magnetic ions with non-magnetic species. In some instances, such disordered systems exhibit what is known as a "spin glass" phase. As the temperature of the system is lowered, the spin dynamics get progressively slower until one reaches a transition temperature where the spins are completely frozen in place, but still randomly oriented. This frozen disorder is analogous to the frozen structural disorder seen in real glasses, hence the name. Spin glass models can also be related to models of such diverse systems as neural networks, biological evolution and the internet!
Geometric frustration arises in magnetic materials when there is no ground state which allows all the pairs of interactions to be satisfied simultaneously. This is most easily illustrated with spins occupying the corners of a triangle interacting with each other antiferromagnetically (preferring to be oppositely aligned). two of the spins may point in opposite directions from each other, thereby satisfying the antiferromagnetic interaction, but the third is then frustrated, unable to choose an ideal configuration. Geometric frustration can lead to a variety of very interesting magnetic properties. Often, a material's magnetic ordering temperature is greatly reduced or even completely suppressed by the frustration. Spin glasses (frozen disorder), spin liquids (dynamic spins) and spin ice (a magnetic analog of water-ice) are some of the more unusual states resulting from geometric frustration.
A superconducting transition edge sensor (TES) can be used to make the most sensitive thermometer which operates in a very narrow temperature range (<5mK). A TES takes advantage of the very sharp transition from normal resistance to superconductivity. Within this transition a very small variation in temperature corresponds to a large change in resistance. When the sensor is thermally balanced at the transition temperature, it can be used to detect very small temperature fluctuations. In order to select an operating temperature, a TES is fabricated with a thin film of normal and superconducting metal. Due to the proximity effect, their relative thicknesses determines the critical temperature of the bi-metal. TES's have many advantages over other thermometers. For example, the TES's size is useful when working in low temperature physics where space is limited in dilution refrigerators and other cryogenic apparatus. TES's are highly sensitive to variations in temperature and energy, the TES's fabricated in our lab are able to measure changes in energies on the order of 10-19J, which is many orders of magnitude better than conventional techniques. High accuracy is important for sensitive measurements, as well as low noise. The TES's made in our group have a noise sensitivity of of less than 1nK/sqrt(Hz). A TES can be used anywhere a high energy sensitive sensor is required, it can be used as a calorimeter to measure a heat change or as a bolometer to detect power absorption.
H. M. Revell, L. R. Yaraskavitch, J. D. Mason, K. A. Ross, H. M. L. Noad, H. A. Dabkowska, B. D. Gaulin, P. Henelius & J. B. Kycia
Evidence of impurity and boundary effects on magnetic monopole dynamics in spin ice
Nature Physics 85, doi:10.1038/nphys2466 (2012)
D. Pomaranski, and J. B. Kycia
Low Temperature Specific Heat Measurements of Frustrated Magnetic Materials
Physics in Canada 68, No. 2: 99-102 (2012)
L. R. Yaraskavitch, H. M. Revell, S. Meng, K. A. Ross, H. M. L. Noad, H. A. Dabkowska, B. D. Gaulin, and J. B. Kycia
Spin dynamics in the frozen state of the dipolar spin ice material Dy2Ti2O7
Phys. Rev. B 85, Issue 18, 020410(R) (2012)
J. A. Quilliam, S. Meng, C. G. A. Mugford, and J. B. Kycia
Evidence of Spin Glass Dynamics in Dilute LiHoxY1-xF4
Phys. Rev. Lett. 101, Issue 18, 187204 (2008)
Please see Google Scholar for a complete list of Dr. Kycia's publications.
1997: PhD, Physics, Northwestern University
1991: MSc, Physics University of Pennsylvania
1989: BSc, Physics, McGill University