|I am a Lecturer in the Division of Physics and Applied Physics, School of Physical and Mathematical Sciences (SPMS), Nanyang Technological University. I received my PhD at the University of Wisconsin-Madison, working with my advisors Sue Coppersmith and Mark Friesen on quantum dot spin qubits in silicon. Prior to that, I was an educator with the Singapore Ministry of Education for almost a good decade. Education is one of my core passions, as is Physics. I work on the theory of solid state quantum devices with applications to quantum information processing. One of my main motivations is to make progress towards a deeper understanding of the foundations of quantum theory. The deeper one goes into the quantum-ness of physical phenomenon, the less intuitive it gets, and the closer to philosophy it becomes. This fascinates me, and I often wonder at the profound meaning behind quantum theory and Zen, both of which have parallels in their view of the nature of reality.|
|Quantum Information and Computation |
In the field of quantum information and computation, some of the quantum computer architectures that I am interested to study include semiconductor quantum dots and hybrid photonic-solid state systems. Such systems hold the promise of scalability due to their small (~100 nm) dimensions as well as the integrability with current microelectronics technologies. Some of the theoretical goals are to understand the performance of various quantum control and entanglement schemes, how decoherence properties and qubit interactions scale with increasing number and connectivity of qubits, and the investigation of novel quantum algorithms. With the scaling up of qubits into a quantum network, it therefore becomes important to understand the behaviour of networks and their properties, and how they perform in applications such as quantum key distribution and quantum state transfer, as well as with novel quantum algorithms. For example, the recently proposed quantum version of Google’s PageRank algorithm was found to outperform the classical version.
Nanoscale Device Physics
In studying how a quantum computer may be realised in solid state architectures, it is natural to study the Physics of nanoscale devices. In this field, beside quantum computing devices, I am interested in spintronics and valleytronics device Physics. In such investigations, it is important to understand the properties of the host material and the architecture of the device. For example, in silicon and graphene that such single electron quantum dot devices may be fabricated in, valley states may play an important role in the device Physics. I am interested to study how valley and spin degrees of freedom may be harnessed to store, manipulate and readout a bit of information.
Foundational Issues in Quantum Mechanics
I am interested in understanding foundational issues in Quantum Mechanics. Is the quantum state description a mere mathematical tool? Does a pure quantum state correspond directly to reality or only some information about a certain aspect of reality, that upon measurement is revealed to us? In the ontological vs epistemological debate over the nature of quantum reality, can we deduce no-go theorems that allow experimenters to test and resolve the issue?
- Dohun Kim, Z.Shi, C.B.Simmons, D.R.Ward, J.R.Prance, T.S.Koh, J.K.Gamble, D.E.Savage, M.G.Lagally, Mark Friesen, S.N.Coppersmith, and Mark A. Eriksson. (2014). Quantum control and process tomography of a semiconductor quantum dot hybrid qubit. Nature, 511, 70.
- Z.Shi, C.B.Simmons, D.R.Ward, J.R.Prance, Xian Wu, T.S.Koh, J.K.Gamble, D.E.Savage, M.G.Lagally, Mark Friesen, S.N.Coppersmith, and M.A.Eriksson. (2014). Fast coherent manipulation of three-electron states in a double quantum dot. Nature Communications, 5, 3020.
- T.S.Koh, S.N.Coppersmith, and Mark Friesen. (2013). High fidelity gates in quantum dot spin qubits. Proceedings of the National Academy of Sciences of the United States of America (PNAS), 110(49), 19695.
- T.S.Koh, J.K.Gamble, M.A.Eriksson, Mark Friesen, and S.N.Coppersmith. (2012). Pulse-gated quantum dot hybrid qubit. Physical Review Letters, 109(25), 250503.
- T.S.Koh, C.B.Simmons, M.A.Eriksson, S.N.Coppersmith, and Mark Friesen. (2011). Unconventional transport in the hole regime of a Si double quantum dot. Physical Review Letters, 106(18), 186801.