Researchers at Stanford University in the Nanoscale and Quantum Photonics Lab are studying new ways to manipulate a unit of quantum information called a qubit. One promising material system for building qubit systems is based on impurities in diamond. Specifically, a small amount of silicon is introduced during growth of the diamond crystal, and under the right conditions a silicon atom will take the place of two carbon atoms. The resulting complex is called a silicon-vacancy (SiV) center in diamond, and it behaves like a qubit which can store quantum information.
Both writing and reading this information is quite challenging with lasers, because the SiV is trapped in the middle of diamond (a highly reflective material). To overcome these challenges, the group nanofabricates tiny suspended beams that look a bit like Toblerone chocolate bars.
Although the silicon vacancy centres are not visible in the micrograph, their presence can be observed. The holes and ridges of the bar have a slight modulation in their repetition length, which has the effect to trap light near the SiV. Systems that exhibit this trapping behavior are called nanocavities and enhance the interaction strength between an incident laser pulse and the SiV. They further enhance the detection efficiency of light emitted by the SiV that indicates the success of manipulating the qubit
Advantages of the Montana Instruments Cryostation
These experiments must be done at cryogenic temperatures, and the Cryostation enables the samples to stay cold for long periods of time without the potentially damaging thermal cycling. Further, the thermal and vibrational stability of the system allows the team to perform long experiments to detect the presence of subtle quantum effects. With the Cryostation specifically, the group takes full advantage of the short working-distance Cryo-Optic objective — moving the 0.9 NA objective right up next to the sample enables vacuum yields collection of nearly all light escaping the sample surface, which is then fed into their optical setup for analysis.Back to news Back to news