- Dr. Yap Yung Szen from Osaka University and,
- Dr. Yasuaki Monnai from The University of Tokyo.
Winner’s comment (By Dr. Yap Yung Szen from Osaka University)
In Kitagawa Lab of Osaka University, we use Nuclear Magnetic Resonance (NMR) and Electron Spin Resonance (ESR) for molecular spin quantum computing research. This means that our experiment setups require extensive use of RF and microwave components and instruments.
An important part of the setup is the resonator and one part of my research is to create a stripline ESR resonator that will allow users to control electron spins quickly before the spin decoheres with time and information is lost irreversibly. Since the electron spins react to the strength of microwave magnetic field, we can control (or “rotate”) the spins quickly using an efficient resonator coupled with sufficient microwave power. The measure of how fast the spins “rotate” is known as Rabi frequency and is represented in hertz.
The flexibility and accuracy of CST MICROWAVE STUDIO® is instrumental to our research work. In our paper, we describe our work to use the software to design, simulate and fabricate a new stripline resonator that efficiently converts microwave power to magnetic field at around 17 GHz. By applying pulses around 1 W, we have demonstrated a Rabi frequency of ca. 210 MHz. Rabi frequencies rarely exceed 100 MHz, especially for ESR spectroscopic experiments, but such high Rabi frequency and a broad bandwidth are useful for quantum computing. By overcoupling the resonator, we were able to increase the bandwidth from around 200 MHz to about 560 MHz, which allows us to use pulses as short as 2 ns when overcoupled. In this paper, we also proposed a new coupling adjustment method for (transmission and reflection type) stripline and micro-stripline resonators, which we believe, offers greater flexibility than conventional methods.
For more information, please have a look at our paper (http://dx.doi.org/10.1016/j.jmr.2013.04.015).