Researchers at IST Austria have built compact photon directional devices. Their micrometer-scale, nonmagnetic devices route microwave photons and can shield qubits from harmful noise.
Qubits, or quantum bits, are the key building blocks that lie at the heart of every quantum computer. In order to perform a computation, signals need to be directed to and from qubits. At the same time, these qubits are extremely sensitive to interference from their environment, and need to be shielded from unwanted signals, in particular from magnetic fields. It is thus a serious problem that the devices built to shield qubits from unwanted signals, known as nonreciprocal devices, are themselves producing magnetic fields. Moreover, they are several centimeters in size, which is problematic, given that a large number of such elements is required in each quantum processor. Now, scientists at the Institute of Science and Technology Austria (IST Austria), simultaneously with competing groups in Switzerland and the United States, have decreased the size of nonreciprocal devices by two orders of magnitude. Their device, whose function they compare to that of a traffic roundabout for photons, is only about a tenth of a millimeter in size, and—maybe even more importantly—it is not magnetic. Their study was published in the open access journal Nature Communications. (DOI: 10.1038/s41467-017-01304-x)
When researchers want to receive a signal, for instance a microwave photon, from a qubit, but also prevent noise and other spurious signals from traveling back the same way towards the qubit, they use nonreciprocal devices, such as isolators or circulators. These devices control the signal traffic, similar to the way traffic is regulated in everyday life. But in the case of a quantum computer, it is not cars that cause the traffic but photons in transmission lines. “Imagine a roundabout in which you can only drive counterclockwise”, explains first author Dr. Shabir Barzanjeh, who is a postdoc in Professor Johannes Fink’s group at IST Austria. “At exit number one, at the bottom, there is our qubit. Its faint signal can go to exit number two at the top. But a signal coming in from exit number two cannot travel the same path back to the qubit. It is forced to travel in a counterclockwise manner, and before it reaches exit one, it encounters exit three. There, we block it and keep it from harming the qubit.”
The ‘roundabouts’ the group has designed consist of aluminum circuits on a silicon chip and they are the first to be based on micromechanical oscillators: Two small silicon beams oscillate on the chip like the strings of a guitar and interact with the electrical circuit. These devices are tiny in size—only about a tenth of a millimeter in diameter—, one of the major advantages the new component has over its traditional predecessors, which were a few centimeters wide.
Currently, only a few qubits have been used to test the principles of quantum computers, but in the future, thousands or even millions of qubits will be connected together, and many of these qubits will require their own circulator. “Imagine building a processor that has millions of such centimeter-size components. It would be enormous and impractical,” says Shabir Barzanjeh. “Using our nonmagnetic and very compact on-chip circulators instead makes life a lot easier.” Yet some hurdles need to be overcome before the devices will be used for this specific application. For example, the available signal bandwidth is currently still quite small, and the required drive powers might harm the qubits. However, the researchers are confident that these problems will turn out to be solvable.
The Latest on: Quantum computing
- Google Claims To Have Invented A Quantum Computer, But IBM Begs To Differon January 22, 2020 at 8:47 pm
Quantum computing would signify an immense shift in processing power, but how close are we to achieving it? (Image: Shutterstock) On Oct. 23, 2019, Google published a paper in the journal Nature ...
- SW/HW co-design for near-term quantum computingon January 22, 2020 at 8:06 am
In this video from ATPESC 2019, Yunong Shi from the University of Chicago presents: SW/HW co-design for near-term quantum computing. The Argonne Training Program on Extreme-Scale Computing (ATPESC) ...
- Synaptic weighting in single flux quantum neuromorphic computingon January 22, 2020 at 3:21 am
Josephson junctions act as a natural spiking neuron-like device for neuromorphic computing. By leveraging the advances recently demonstrated in digital single flux quantum (SFQ) circuits and using ...
- Quantum Computing Technologies Market Latest Advancements and Future Growth 2020 to 2026on January 21, 2020 at 11:33 pm
Global Quantum Computing Technologies Market Size, Status and Forecast 2020-2026 "Quantum Computing Technologies Market" research report provides an actual industry viewpoint, future trends and ...
- New technique to study molecules and materials on quantum simulator discoveredon January 21, 2020 at 10:15 am
The ground-breaking new technique, by physicist Oleksandr Kyriienko from the University of Exeter, could pioneer a new pathway towards the next generation of quantum computing. Current quantum ...
- Quantum computing: Opening new realms of possibilitieson January 21, 2020 at 3:40 am
Without it, we would not have such marvels as atomic clocks, computers, lasers, LEDs, global positioning systems and magnetic resonance imaging, among many other innovations. It is in the domain of ...
- How companies like Google and IBM plan to make money from quantum computingon January 20, 2020 at 11:02 am
Here's how quantum computing works, and how it could change everything from Wall Street to Big Pharma and beyond.
- How companies like Google and IBM plan to profit from quantum computingon January 20, 2020 at 11:01 am
In October 2019, Google made a big announcement. It announced its 53-qubit quantum computer named Sycamore had achieved 'quantum supremacy.' That's when quantum computers can complete tasks ...
- WEF's Global Risk Report warns of dark side of IoT, AI, quantum computingon January 16, 2020 at 1:16 pm
World Economic Forum report once again lists cyberattacks as one of the top threats facing the world in 2020 - alongside climate change, extreme weather and natural disasters.
- 5 tech trends in 2020: Quantum computing, AR/VR, 5G, and moreon January 16, 2020 at 9:07 am
This year will see the commercialization of high-level tech that gained ground in 2019, CB Insights found. The top tech trends for 2020 cover a wide array of areas including quantum computing, ...
via Google News and Bing News