Processing photons for milliseconds of up to 9,000 years on a supercomputer

Given a real beam of light, the ray transmitter divides it into two parts.  Looking at individual photons, the behavior becomes more complex.
Zoom / Given a real beam of light, the ray transmitter divides it into two parts. Looking at individual photons, the behavior becomes more complex.

Ars Technica’s Chris Lee has spent a large part of his life playing with lasers, so he’s a huge fan of photon-based quantum computing. Even with the advancement of various forms of physical devices such as superconducting wires and trapped ions, it has been possible to achieve this find it flowing About an optical quantum computer developed by a Canadian startup called Xanadu. But, in the year since Xanadu described their devices, companies using that other technology have continued to make progress Reduce error ratesAnd the exploration the new TechnologiesAnd the Increasing the number of qubits.

But the advantage of optical quantum computing hasn’t gone away, and now Xanadu is back with a reminder that it hasn’t gone away either. Thanks to some tweaks to the design he described a year ago, Xanadu is now sometimes capable of performing operations with more than 200 qubits. It has been shown that simulating the behavior of just one of those processes on a supercomputer would take 9,000 years, while an optical quantum computer could do it in a few tens of a thousandth of a second.

This is a completely contrived standard: just like Google quantum computer act, a quantum computer only exists while a supercomputer is trying to simulate it. The news here is more about the possibility of expanding Xanadu devices.

stay in the light

The advantages of quantum computing based on optics are significant. Almost all modern communications rely on optical devices at some point, and improvements in that technology have an opportunity to apply directly to quantum computing devices. Some of the manipulations we may need can be done with devices so miniature that we can engrave them on a silicon chip. All devices can be kept at room temperature, avoiding some of the challenges of getting signals in or out of equipment located near absolute zero.

Xanadu seems convinced that these advantages are large enough to build a company around which makes sense. devices that me labeled last year It relies on a single chip to put photons into a certain quantum state and then force pairs of photons to interact in their entanglement ways. These interactions form the basis of qubit processors that can be used to perform calculations. The photons can then be sorted based on their state, with the number of photons in each state providing the answer to the computation.

There are challenges to scaling up this technology. Since photons can only interact in pairs, adding another photon means you have to include enough hardware features for their necessary interactions. This means that scaling the processor to higher qubits involves scaling all of these devices on the chip. It’s not a problem now, but it can easily be a problem as things scale from hundreds to thousands.

Choose your own adventure

This analogy is perhaps why the new Xanadu system, called Borealis, includes a major revision of the architecture. Her former deities used a set of identical photons that all entered the chip in parallel and traveled through them simultaneously. In Borealis, photons enter the system sequentially and follow a path a bit like a “choose your own adventure” game.

The first piece of gear that the photons hit is a programmable beam splitter, which can serve two functions. If two photons simultaneously reach it, they can interfere with each other and become entangled. Depending on its state, the beam splitter can deflect photons out of the main path into a ring of optical fibers. Traveling around that ring adds a delay to the photon’s travel, allowing it to exit the fiber at the same time a new photon arrives at the beam splitter, allowing it to be entangled with a subsequent photon.

Once the first beam interval is exceeded, the photons act out in a second, with a longer loop of optical fibers causing a longer delay of any photons you send out. Then to a third with a longer loop. Optional delays allow the photons to entangle with other photons that do not reach the devices until long after their arrival. As presented by Xanadu, each of Borealis’ three beam splitters is like adding an extra dimension to the entanglement matrix, going from non-entanglement to three dimensions of potential entanglement.

Once through, the photons are sorted based on their properties and sent to a series of detectors. The detectors keep track of how many photons arrive and when, which will provide an answer to any calculations you make. Depending on the configuration, it can handle more than 200 individual photons as part of a calculation.