QUANTUM COMPUTING FEATURE
could also be very relevant to other applications of quantum technologies, such as sensing. “One potential application
could be building a portable sensor with miniaturised photon sources and sensors integrated on-chip with a Rydberg atom chamber, and then use it to detect, for example, small changes in electromagnetic or gravitational fields,” he explained. “So having these faster quantum gates could increase the potential of some of these sensors, for example in positioning, navigation, and timing applications ”
“The ultrafast quantum gates of 6.5 nanoseconds, achieved using cold-atom hardware, are more than two orders of magnitude faster than the noise and thus can ignore its effects,” confirmed the researchers in their announcement of the work. “The cold-atom quantum computer has revolutionary potential in that it can be easily scaled up to larger scale while maintaining high coherence compared to superconducting and trapped-ion quantum computers. This realisation of the world’s fastest ultrafast gate, achieved using a completely new method of manipulating two artificial crystals of micron- spaced atoms cooled to almost absolute zero using an ultrafast laser, is expected to greatly accelerate worldwide attention to cold-atom hardware.”
A second opinion Electro Optics approached Martin Weides, Professor of Quantum Technologies at the University of Glasgow, to find out whether the announcement was indeed as significant as the researchers made it out to be. He began by remarking on the progress that has been made in
www.electrooptics.com | @electrooptics
“In the field of cold-atom quantum computers, this work shows speeds 100 times faster than those achieved before”
the field of cold-atom quantum computers in recent years: “Every cold-atom computer uses lasers to both trap (optical tweezers) and cool atoms to micro-Kelvin temperatures, which all takes place in vacuum (the powerful lasers are positioned outside the vacuum on an optical table). “The laser stability is
therefore key, and it is this that has really come along in recent years. There is an increasing global effort to build quantum computers based on cold atoms.” However, according to
Weides, the weakness of such quantum computers has so far been the time it takes to implement a quantum gate, which has traditionally been much longer than the typical gate times achieved on superconducting platforms – such as the aforementioned system developed by Google AI. “But now, with this work,
they have achieved even shorter gate times, meaning the quantum algorithm can be
operated as fast as on the other platforms,” he remarked. “In the field of cold-atom quantum computers, this work shows speeds 100 times faster than that achieved before. This is especially significant seeing as previous improvements to gate time have been more incremental, say, going from 50 nanoseconds to 20 or 15 nanoseconds – whereas here, it’s down to just a few nanoseconds, which is such a dramatic improvement. This work is therefore very important for the field of cold-atom quantum computers.” “It’s maybe of lesser interest
to the likes of IBM or Google, but I think it will certainly accelerate the interest in cold-atom quantum computers and lead to more research,” Weides continued. “There might even be faster gates possible with continued hardware improvements and different schemes to implement two- and many-qubit gates. So I think academically and also, economically, it’s very interesting.” Weides also highlighted that
the work relating to Rydberg atoms discussed in the paper
Further fidelity required However, despite the many benefits realised by the exceptionally fast quantum gate times achieved by the Japanese researchers, Weides doesn’t believe the work is necessarily an absolute “game changer” in the field of quantum computers. “While this paper demonstrates the fastest two- qubit gate ever achieved, the gate fidelity is not actually quite as good as the two-qubit gates demonstrated by Google or other players in the field of quantum computing – so that’s a potential drawback,” he explained. “However, the researchers do appear to have planned a strategy on how to address this. In addition, the fidelity of cold- atom quantum computers in general is currently not quite good enough to build fully functional gate-based quantum computers (such as those being developed by IBM and Google AI) capable of performing the wide array of tasks these devices are promised to deliver. Instead, they are currently more suited to the field of quantum simulation – simulating physical systems using hundreds of qubits in which many-body physics experiments can be performed. And so in my opinion – until the fidelity of cold-atom quantum computers improves sufficiently – this is the practical application of quantum computing that this new work will likely be most relevant to.” EO
November 2022 Electro Optics 31
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58
