Diamond devices: High voltage, low leakage SBD; stretching qubits; optical data storage.
Researchers from the University of Illinois at Urbana-Champaign developed diamond p-type lateral Schottky barrier diodes they say have the highest breakdown voltage and lowest leakage current compared to previous diamond devices. The diamond device can sustain high voltage, approximately 5 kV, although the voltage was limited by setup of measurement and not from the device itself. In theory, the device can sustain up to 9 kV.
“We built an electronic device better suited for high power, high voltage applications for the future electric grid and other power applications,” said Zhuoran Han, a graduate student at UIUC. “And we built this device on an ultra-wide bandgap material, synthetic diamond, which promises better efficiency and better performance than current generation devices. Hopefully, we will continue optimizing this device and other configurations so that we can approach the performance limits of diamond’s material potential.” [1]
Researchers from University of Chicago, Argonne National Laboratory, and Cambridge University stretched thin films of diamond to create quantum bits that can operate as part of a quantum network with significantly reduced equipment and expense. The change also makes the qubits easier to control.
To stretch diamond out at a molecular level, they laid a thin film of diamond over hot glass. As the glass cools, it shrinks at a slower rate than the diamond, slightly stretching the diamond’s atomic structure. While the process only moves the atoms apart a tiny amount, it enables them to hold their coherence at temperatures up to 4 Kelvin (or -452°F) — a temperature that, while still very cold, can be achieved with less specialized equipment.
“Most qubits today require a special fridge the size of a room and a team of highly trained people to run it, so if you’re picturing an industrial quantum network where you’d have to build one every five or 10 kilometers, now you’re talking about quite a bit of infrastructure and labor,” said Alex High, assistant professor with the Pritzker School of Molecular Engineering at the University of Chicago. The higher temperature means “an order of magnitude difference in infrastructure and operating cost.”
Additionally, the change also makes it possible to control the qubits with microwaves. Previous versions had to use light in the optical wavelength to enter information and manipulate the system, which introduced noise and meant the reliability wasn’t perfect. By using the new system and the microwaves, however, the fidelity went up to 99%. [2]
Physicists at The City College of New York found that by multiplexing the storage in the spectral domain, the optical data storage capacity in diamonds can be improved. “It means that we can store many different images at the same place in the diamond by using a laser of a slightly different color to store different information into different atoms in the same microscopic spots,” said Tom Delord, postdoctoral research associate at CCNY. “If this method can be applied to other materials or at room temperature, it could find its way to computing applications requiring high-capacity storage.”
The team focused on diamond ‘color centers,’ atomic defects that can absorb light and serve as a platform for quantum technologies. “What we did was control the electrical charge of these color centers very precisely using a narrow-band laser and cryogenic conditions,” explained Delord. “This new approach allowed us to essentially write and read tiny bits of data at a much finer level than previously possible, down to a single atom.”
The approach is also reversible. “One can write, erase, and rewrite an infinite number of times,” said Richard G. Monge, a postdoctoral fellow at CCNY. [3]
References
[1] Z. Han and C. Bayram, “Diamond p-Type Lateral Schottky Barrier Diodes With High Breakdown Voltage (4612 V at 0.01 mA/Mm),” in IEEE Electron Device Letters, vol. 44, no. 10, pp. 1692-1695, Oct. 2023, http://dx.doi.org/10.1109/LED.2023.3310910
[2] Xinghan Guo et al, “Microwave-based quantum control and coherence protection of tin-vacancy spin qubits in a strain-tuned diamond membrane heterostructure.” Physical Review X, Nov. 29, 2023. https://dx.doi.org/10.1103/PhysRevX.13.041037
[3] Monge, R., Delord, T. & Meriles, C.A. Reversible optical data storage below the diffraction limit. Nat. Nanotechnol. (2023). https://doi.org/10.1038/s41565-023-01542-9
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