Latest news with #errorcorrection
Globe and Mail
3 days ago
- Business
- Globe and Mail
Canada's Xanadu achieves worldwide first with error-resistant quantum chip
Toronto startup Xanadu Quantum Technologies Inc. is reporting a new milestone in the effort to develop a form of light-based quantum computing that can operate at commercial scale. For the first time anywhere, Xanadu researchers have created a single chip that embodies a powerful type of error-detection code in a pulse of laser light. If a number of such chips could be harnessed together, it would open the door to a quantum computer that can deliver reliable results with practical value. 'This is something that's been on our roadmap for a long time,' Zachary Vernon, Xanadu's chief technology officer for hardware, told The Globe and Mail. A technical description of the chip was published Wednesday in the journal Nature. The development is significant 'because the chip platform is supposed to be scalable,' said Daniel Soh, an associate professor of optical science at the University of Arizona in Tucson. 'In the future, we will need millions or billions of this kind of devices on a chip. This result is a massive step towards that goal,' said Dr. Soh, who is not affiliated with Xanadu. Canada 'a sweet spot' for growing quantum computing industry, expert says Christian Weedbrook, Xanadu's founder and chief executive officer, said the development means it is possible to envision a quantum-computing system operating at the scale of a data centre, with some 5,000 servers fitting into a facility less than 10,000 square metres in size. 'We're also thinking ahead to how we can add more density in there, so that'll change,' he said. Earlier this year Xanadu published a result showing how its form of quantum computing could be easily modularized. This latest step is aimed at making a machine large enough to solve relevant problems but not so large that it becomes impractical for commercial purposes. It is the latest example of a shift in the focus and tempo of advancements in the quantum computing world. Overall, the goal remains to create a computer that runs on qubits – interconnected physical elements that exhibit quantum behaviour – instead of the standard bits of a conventional digital system. Where a bit can be used to represent a one or a zero in a mathematical calculation, a qubit can be a mixture of both. This dual nature, when combined with many other qubits, is what allows a quantum computer, in principle, to vastly outperform a conventional computer at certain kinds of calculations that are important for data security and other applications. While various companies, including Google, IBM and Microsoft, have experimented with different types of qubits, all of them face the same challenge: Quantum systems are sensitive to disturbance and difficult to isolate from the rest of the world, which makes quantum computers especially error-prone. To counter this, qubits can be linked to check each other for signs of failure during a calculation. But the price for such redundancy is that many more qubits are needed to build a reliable computer powerful enough to solve real-world problems. More recently, teams have sought to exploit various mathematical codes, which are ways of tying qubits together, to make error correction more robust. Of particular interest are Gottesman-Kitaev-Preskill (GKP) codes. First proposed in 2001, they are challenging to implement but especially amenable for quantum computer builders such as Xanadu, whose machines use qubits made of light moving through a fibre-optic network. Xanadu's new chip corrals incoming particles of light, called photons, into a quantum state that allows them to work together to form a GKP qubit. The chip has four outputs, three of which are connected to detectors that can reveal whether the fourth is in a state that would allow it to be useful for a quantum calculation. In a working quantum computer, such chips would provide an initial layer of error detection that would then be further augmented by other error-correction techniques when chips are combined. Similar strategies are being explored by other companies. Last week, Nord Quantique, based in Sherbrooke, Que., demonstrated that it had successfully encoded microwave photons bouncing around inside a metal cavity with a GKP code. Meanwhile, Xanadu still has more obstacles to overcome. Chief among them is finding ways to overcome signal loss, which occurs when photons are absorbed by the materials they are moving through. In addition to making its light-based technology work, Xanadu and direct competitors such as PsiQuantum, Corp. of Palo Alto, Calif., are racing against big tech companies developing computers with qubits that rely on special superconducting materials kept at extremely cold temperatures. Light-based systems offer a different set of advantages, including the fact that they can operate at room temperature. While no system has yet emerged as a clear winner, Dr. Soh says light-based quantum computers may end up inching ahead because once the key technical challenges are solved, they will be easier to scale up.
Globe and Mail
29-05-2025
- Business
- Globe and Mail
Quebec startup shows progress toward practical quantum computing
Julien Camirand Lemyre wants to correct the errors in his way. To be clear, this is not a quest for personal improvement. It's a technical challenge and, for the nascent quantum computing industry, an extremely important one. Mr. Lemyre is a PhD physicist and chief executive officer of Nord Quantique, a startup based in Sherbrooke, Que. Since 2020, he has set his company's sights on overcoming a key obstacle that stands in the path of commercial quantum computing: the technology's propensity for making mistakes. On Thursday, Nord Quantique announced it had taken an important step on its path toward surmounting that barrier. The company has successfully used one of its own quantum devices to encode a form of error detection for the first time. Bigger players, including Google, Microsoft and Amazon, are working on the same problem as they seek to advance their own quantum systems. What's different about Nord Quantique is that the hardware doing the checking is the same hardware doing the calculating. The experimental result suggests that larger, commercially relevant quantum computers can be constructed from similar components. If so, those computers might occupy only a modest amount of space – something like a standard data centre rather than a football-field size complex that some fear will be required to get other types of quantum systems to run reliably. 'We think there are better ways to quantum error correction,' Mr. Lemyre said. 'This ties in with our philosophy of really working on something that we think is worth scaling up.' The company's announcement, together with an accompanying scientific paper, is the latest step in what has become a industry-wide push to tackle error correction, also called fault tolerance. Fault tolerant quantum computers have yet become a practical reality, but they are an attractive business proposition because they are expected to one day perform various kinds of calculations that are out of reach of conventional digital systems. Potential applications range from data security, to drug discovery to forecasting, among other areas. Yet the same properties that make quantum computers powerful also make it easy for them to fail. Ordinary computers use bits – the electronic components that represent the 1s and 0s of a digital operation. In a quantum system, the bits are replaced with qubits, which are more versatile and more finicky. Thanks to the slippery rules of quantum physics a qubit needn't be a one or a zero, but can be a bit of both. But this ambiguous state of being, so essential for quantum computation, is easily disrupted by outside influences such as vibration or heat. Microsoft creates chip it says shows quantum computers are 'years, not decades' away The standard way of dealing with this is to dedicate other qubits to keep tabs on the first one. But this gets complicated and costly. For every qubit required to perform a calculation, more than 1,000 may be required for error correction. Imagine a Hollywood celebrity with an entourage that would fill an entire hotel and you can see how the problem multiplies as more celebrities join the party. Nord Quantique uses a different kind of qubit than many other systems, involving microwaves in a supercooled cavity. The microwaves consist of individual particles, or photons, that have different ways of bouncing around in the cavity called modes. What Nord Quantique has shown in its latest work is that these modes can be used for a type of error detecting code called Tesseract without the need for additional hardware. Mr. Lemyre said there are ways in which the approach can be further improved, such as by adding more photons to the cavity. And the system would draw only a fraction of the energy needed by other approaches. Yvonne Gao, an assistant professor at the National University of Singapore who is familiar with the company's work, said that the work represents good progress along one possible path toward a fault tolerant quantum computer. She said Nord Quantique has helped the field by adding to the diversity of approaches to error correction, while carving out its own niche. 'It's a very smart choice not going head on with the other people working on other flavours' of the problem, she said. While some larger companies have made huge investments in quantum computing, it is unclear which approach is most likely to succeed. That means smaller startups with novel technologies to explore may ultimately be the ones who find the way forward. Three Canadian companies vying for U.S. quantum computing funding as race to develop technology heats up Daniel Gottesman, a theoretical physicist at the University of Maryland who played a part in developing the codes that Nord Quantique and others are using for error correction, said that it was surprising that no clear winner has yet emerged among the various approaches being tried. One reason for this, he said, is that the difficulty in building and controlling such systems is challenging enough that even the best-resourced companies cannot zoom ahead, but instead must work methodically at improving error rates and increasing the number of qubits in their devices. 'That takes time and gives other people time to do that work as well,' he said. Nord Quantique is not the only Canadian company in the error correction game. Last February, Photonic Inc. of Coquitlam, B.C., publicized its approach to the problem, which builds on an alternative strategy for tying qubits together known as QLDPC (quantum low-density parity check) codes. This class of codes is well suited to Photonic's quantum computing hardware, in which qubits are based on the spins of carbon atoms that reside within silicon chips. Because the chips can be interconnected with light guided by fibre optics, the qubits do not need to be physically adjacent to one another to be linked. This means the task of error correction can be spread out, creating opportunities to harness groups of qubits in more efficient ways. Housed in a non-descript industrial unit east of Vancouver, Photonic has grown its head count to 150 since coming out of stealth mode 18 months ago. The company is now preparing to expand into a larger building next door to facilitate its hardware development. Together with Nord Quantique and Xanadu Quantum Technologies Inc. of Toronto, Photonic is one of the Canadian companies to be selected by the U.S. Defense Advanced Research Projects Agency (DARPA) to compete for support in developing quantum computing technologies. Stephanie Simmons, who founded Photonic in 2016 and leads its technology development, said that despite the challenge, the reason for the increasing sense of excitement in the field is clear. 'Every time you commercialize a branch of physics it changes everything,' she said.
