The path to quantum supremacy is complicated by a fairytale challenge – how to hijack a cloud without changing its shape?
The potential solution sounds almost as fantastic as the problem. You could lead the cloud to dance as it travels to the rhythm of a unique material known as a time crystal.
Krzysztof Giergiel and Krzysztof Sacha of Jagiellonian University in Poland and Peter Hannaford of Swinburne University of Technology in Australia propose a new kind of “time” circuit that could be tasked with preserving the nebulous states of qubits as they are carried by storms. quantum logic.
Unlike descriptions of objects that have clearly defined locations and motions, the same-particle quantum perspective describes properties such as its position, momentum, and rotation as a blur of probabilities.
This “cloud” of possibilities is best understood in isolation. As the particle interacts with its environment, its range of possibilities changes like the probability of a runner winning the 100-meter sprint at the Olympics, until eventually only one outcome is observed.
Just as a classical computer can use the binary states of particles as “on-off” switches in logic gates, quantum computers can theoretically use the propagation of uncertainties in a particle to quickly solve their own kinds of algorithms, many of which would be impractical. or even impossible to solve the old-fashioned way.
The challenge is to keep this quantum cloud of possibilities – referred to as a qubit – coherent for as long as possible. With every bump, every electromagnetic breeze, comes an increased risk of errors that will ruin the number crunching process.
Practical quantum computers require hundreds, if not thousands, of qubits to remain intact for long periods of time, making a full-scale system a monumental challenge.
Researchers have looked at various ways to make quantum computing more robust, from either locking down individual qubits to protect them from decoherence to building security networks around them.
Now physicists Giergiel, Sacha and Hannaford have described a new approach that turns quantum computers into a qubit symphony led by the baton of a very special kind of conductor.
Time crystals are materials that transform into repeating patterns over time. Theorized more than a decade ago as curiosities, versions of these “ticking” systems have since been developed using gentle laser nudges and ultracold clusters of atoms, where flashes of light send particles into periodic oscillations that defy laser timing.
In a paper available on the arXiv with preliminary reviews, a trio of physicists proposes to use the unique periodicity of the time crystal as the basis for a new kind of “timetronics” circuit. This periodicity, which is used to guide the subtle waves of vast amounts of information-laden qubits, could help reduce the random collisions that are responsible for many errors.
Such a temporal circuit of perpetually drifting qubits would make it easy to steer almost any computer particle into the path of another particle, intertwining their quantum capabilities in useful rather than error-enforcing ways.
While the proposal remains purely theoretical, the team showed how the physics of clusters of potassium ions cooled to near-absolute temperatures and controlled by a laser pulse could provide an “orchestra” for the qubits to dance to.
Translating the idea into a practical, full-scale quantum computer would require years of innovation and experimentation if it works at all.
Now that we know that at least some types of time crystal exist and can be used for practical purposes, the challenge of carrying a cloud may not be such a fairytale quest after all.
This study is available on the arXiv pre-review server.