In quantum computing, qubits (the fundamental unit of information) can be built using electron spin as their basis. Data stored in qubits may need to be transferred between quantum nodes in a network before it can be processed or stored.
The electrons might be carried by sound waves, which is now a viable transportation alternative. “We proved it for the first time more than 10 years ago,” said Institute Néel director and Grenoble native Christopher Bauerle.
Nonetheless, there was a major flaw in this method. Trying to forecast the location of an electron in a sound wave is challenging because, like any wave, it has a sinusoidal structure with multiple peaks and valleys.
Now, Bauerle and his team have solved this issue by deliberately creating waves with only one possible extreme value. He said that they used a method called Fourier synthesis to create a single minimum and maximum regardless of whether they applied positive or negative voltage.
According to Bauerle, these focused sound waves are analogous to laser pulses. Time-resolved measurements are accomplished by stimulating a system with a brief laser pulse. When it comes to our system, we employ a similar method based on the utilisation of sound. It’s possible to pinpoint the electron’s arrival at a node thanks to the auditory pulse,” he explained.
An expert on nanoelectronics in Berlin, Paulo Santos of the Paul Drude Institute for Solid State Electronics, compares the method to surfing. The electron qubit travels through the quantum network by “riding the surface acoustic wave,” as an observer named Santos put it who was not involved in the study.
stirring up controversy
These noises were produced using a chip with quantum nodes placed in a gallium-arsenide crystal and connected to two gold-plated electrodes printed on a piezoelectric substrate. By providing a changing voltage between the electrodes, an electric field is created. The piezoelectric material is deformed by the fluctuating electric field, causing surface acoustic waves to be produced. To aid in their movement, electrons are followed by a moving electric field (produced by the inverse piezoelectric effect).
Bauerle enumerated a number of benefits associated with using this technology, which is effective between 20 mK and 1 K. “At the speed of sound, or around 3,000 metres per second, the electrons are shuttled from node to node. Thanks to this, and the regulated and exact nature of electron transmission, we may change the quantum information in real time. When compared to the photonic quantum system, in which modifications must be performed in advance due to the prohibitively high rate at which information is conveyed (the speed of light), “His words.
The vast magnitude of the waveform also suggests that this method may be amenable to scaling up. They were able to obtain a transmission efficiency of 99.4 percent, and Bauerle claimed that “a single acoustic wave can carry electrons from several quantum nodes at the same time.”
The capacity to precisely move qubits and alter them on the fly on a chip, as Santos claims, might have a wide range of future applications. “The subsequent crucial step is a public display of entanglement between these aerated qubits. Moving this technology from gallium arsenide to other materials like silicon will also be a major undertaking.”
However, he cautioned that it might be several years before this knowledge is put to use.
The use of photons, superconducting qubits, and cold atoms are some of the additional methods Santos mentioned for processing quantum information in addition to electron spins. He mentioned that photon qubits will still be widely used in quantum computing.
“The vast existing infrastructure for photon-based quantum processing has attracted a larger workforce. A good example is the integrated optics found in silicon-based processors. Electron surfing is compatible with on-chip integration and can take use of these breakthroughs “he stated, implying that progress in one may assist development in the other.