Scientists propose quantum computers with a simpler design

A series of practical questions led researchers to explore the possibility of building simpler quantum computers. like this machinesNowadays, construction is often complex, difficult to measure, and requires temperatures cooler than interstellar space For work, many scientists have been considering alternatives that can overcome these challenges.

Among the solutions that were found was the creation of quantum computers that work on the basis of photons – particles of light that can easily transmit information from one place to another. In this way, optical quantum computers can operate at room temperature, which is a promising approach.

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However, although people have succeeded in creating individual quantum “logic gates” for photons, building a large number of gates and reliably linking them to perform complex calculations is daunting.

The project proposes the use of accessible components in new quantum computers

Researchers at Stanford University in California have proposed a more straightforward design of optical quantum computers using affordable components, according to a published article. in the scientific journal Visual This Monday (29).

According to the publication, the proposed project uses a laser to manipulate a single atom which can in turn change the state of photons through a phenomenon called “quantum teleportation.”

This atom can be reset and reused for many quantum gates, eliminating the need to build several separate physical gates, greatly reducing the complexity of building a quantum computer.

“Normally, if you wanted to build a quantum computer, you would have to take thousands of quantum emitters, make them completely indistinguishable, and then combine them into a giant photonic circuit,” said Ben Bartlett, Ph. Physics and lead author of the article. “As with this project, we only need a few relatively simple components, and the machine does not increase in size with the size of the quantitative program you want to run.”

This extremely simple design, according to Bartlett, requires only as few equipment as a fiber optic cable, a beam splitter, a pair of optical switches and an optical cavity.

The site also highlights PhysFortunately, these ingredients already exist and are commercially available. They are constantly being revised as they are used in various applications beyond quantum computing. For example, telecommunications companies have been improving fiber optic cables for years.

“What we are proposing here is to build on the efforts and investments that people have made to improve these components,” said Shanhui Fan, a professor at the Joseph College and Hon Mae Goodman School of Engineering and senior author of the article. “They are not new components specifically for quantum computing.”

Learn about the project details

The design consists of two main sections: a storage ring and a publishing unit. The storage ring, which functions similarly to the memory of a regular computer, is a ring of optical fibers containing several photons that travel around the ring.

Similar to the bits that store information in a traditional computer, in this system, each photon represents a quantum bit, or “qubit”. The direction of the photon’s displacement around the storage ring determines the qubit value, which can be 0 or 1. Moreover, since photons can exist in two states at the same time, a single photon can simultaneously flow. Both directions, also represent a set of two values ​​of 0 and 1 at the same time.

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According to the researchers, they can manipulate the photon by directing it from the storage ring to the scattering unit, where it travels into a cavity containing a single atom.

Next, the photon interacts with the atom, causing the two to “entangle”, in a quantum phenomenon in which two particles can influence each other, even at great distances.

Then the photon returns to the storage ring, and laser Changes the state of the atom. Since the atom and the photon are entangled, the processing of the atom also affects the state of the photon associated with it.

“By measuring the state of the atom, you can teleport the processes to the photons,” Bartlett said. “So we only need one atomic qubit that can be controlled and that we can use as a proxy to indirectly deal with all the other optical qubits.”

Since any quantum logic gate can be assembled into a series of operations on the atom, it is possible, in principle, to run any quantum program of any size with a single controllable atomic qubit.

To run a program, the code is translated into a series of operations that direct the photons to the scattering unit and manipulate the atomic qubits. Because it is possible to control how the atom and photons interact, the same device can run many different quantum programs.

“For many optical quantum computers, gates are the physical structures that photons pass through, so if you want to change the software that’s running, that often involves physically reconfiguring the hardware,” Bartlett said. “Whereas, in this case, you don’t need to change the hardware—just give the machine a different set of instructions.”

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