Figure outlining the overall system, including the V-MTJ chip and the ASIC along with their respective printed circuit boards. Credit: Duffee et al.
Probabilistic Ising machines (PIMs) are advanced and specialized computing systems that could tackle computationally hard problems, such as optimization or integer factorization tasks, more efficiently than classical systems. To solve problems, PIMs rely on interacting probabilistic bits (p-bits), networks of interacting units of digital information with values that randomly fluctuate between 0 and 1, but that can be biased to converge to yield desired solutions.
A class of PIMs that are intensively investigated use magnetic devices to inject randomness into a digital transistor-based circuit. While these systems have been found to be promising for the rapid resolution of various domain-specific and advanced problems, their large-scale design and reliable fabrication have so far proved challenging. This is primarily because their upscaling requires the precise control of small magnetic moments and often also entails the use of large circuits that convert digital signals into analog voltages and other additional components.
Researchers at Northwestern University and other institutes recently developed a new application-specific integrated circuit (ASIC) that could be used to create better performing probabilistic computers. In a paper published in Nature Electronics, they presented a probabilistic computer based on the new circuit and showed that it could perform integer factorization tasks.
“We were interested in exploring how one could build a scalable probabilistic computer by custom-designing an ASIC using foundry CMOS technology,” Pedram Khalili Amiri, senior author of the paper, told Tech Xplore.
“Our intuition was that by taking advantage of the digital CMOS platform and the high transistor densities available in today’s semiconductor technology, one could eventually build very large-scale probabilistic computers that can tackle problems related to, for example, combinatorial optimization. As a first step, we decided to try out these ideas, and develop the computing architecture and design approach, using a less advanced (130 nm) foundry node.”
When reviewing previous literature in the field and experimenting with probabilistic computing architectures, Amiri and his colleagues realized that, despite its numerous advantages, CMOS technology does not appear to be well-suited for creating random bit sequences. Notably, the creation of these random sequences is central to the functioning of probabilistic computers.
To overcome this limitation of CMOS technology, the researchers adapted voltage-controlled magnetic tunnel junctions (V-MTJs), hardware components that they introduced in their earlier work and had previously applied to the creation of magnetic random-access memory (MRAM) devices. They changed some elements of these devices so that they would serve as high-throughput and compact sources of randomness (i.e., entropy).
“Our probabilistic computer consists of an array of bistable probabilistic elements (called probabilistic bits or p-bits),” explained Amiri. “The interactions between these p-bits can be programmed so that the p-bit network (called a probabilistic Ising machine or PIM) collectively searches through the solution space of a problem. Our p-bits are implemented using digital CMOS circuitry on our ASIC and use bit sequences read from an adjacent V-MTJ chip to provide the required randomness. The energy minimum of the PIM is designed to correspond to the solution of the computing problem of interest.”
Figure showing the ASIC that was used in this experiment. Credit: Duffee et al.
The new probabilistic architecture developed by Amiri and his colleagues could theoretically be used to efficiently tackle many real-world problems, including various optimization tasks. As part of their study, however, the team specifically applied their architecture to integer factorization tasks, which are known to be very challenging to solve computationally.
“This was a good place to start, mainly because there is only one correct solution to be found in the entire energy landscape, and because it is easy to check whether we found the right factors or not,” said Amiri. “The same approach, however, can be applied to many other computing problems.”
Two central advantages of the architecture developed by this research team are that it is digital and synchronous. This is in contrast with most other PIMs introduced in earlier works.
“This means that the probabilistic computer works with a clock that determines a well-defined time interval upon which p-bits can update and does not require area-consuming circuits such as digital-to-analog converters,” said Amiri. “In addition, the use of V-MTJs, which are currently implemented in a separate chip from the ASIC but can eventually be integrated within it, saves area and can provide high-throughput random bit sequences to the p-bits.”
V-MTJs, the components that Amiri and his colleagues used to create their architecture, were found to be inherently more robust against device-to-device variations when used to generate random bits compared to other spintronic random bit generators used in the past. The team’s initial findings were highly promising, highlighting the promise of their approach for creating probabilistic computers.
Notably, although it relies on VMTJs, the new approach is also compatible with established CMOS manufacturing processes and digital design strategies. In the future, it could contribute to the large-scale fabrication of PIMs that could solve a wide range of real-world optimization problems faster and more efficiently.
“Our next step will be to adapt this design to implement problems other than factorization,” added Amiri. “For example, we have a chip in the works that is tailored to other optimization problems with real-world significance. In addition, we plan to integrate the V-MTJs directly on the CMOS in a more advanced foundry node, which would allow us to make the probabilistic computer even more compact.”
Written for you by our author Ingrid Fadelli, edited by Gaby Clark, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive.
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More information:
Christian Duffee et al, An integrated-circuit-based probabilistic computer that uses voltage-controlled magnetic tunnel junctions as its entropy source, Nature Electronics (2025). DOI: 10.1038/s41928-025-01439-6. On arXiv: DOI: 10.48550/arxiv.2412.08017
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New design tackles integer factorization problems through digital probabilistic computing (2025, September 22)
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While the Fire TV Stick is a good choice for Prime Video, it plays well with basically all of the major streaming services you’d expect, including Netflix, Disney+, and HBO Max. The previous generation had just 8 GB of storage, but the new model’s upgraded 16 GB means you won’t have to choose which apps to keep and which to delete. If you have a compatible controller and an Xbox Game Pass subscription, you can even stream games directly to the Fire TV Stick right from the cloud. With some help from Wi-Fi 6E, apps will download faster and stream at higher quality with less buffering, as long as your router supports it.
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“Opportunities like this in tech don’t come up that frequently,” Azzurri Group digital and technology director Jim Hingston says of US-themed restaurant chain Dave’s Hot Chicken.
“You look at the power of the brand, the demand for it, the opportunity we have – my challenge is how do I make tech really a catalyst for the growth and allow us to roll out stores in new markets and territories.”
Hingston chatted to Computer Weekly in the build-up to his appearance on a panel at Retail Technology Show 2026, where he intends to join a discussion on the changing face of digital and tech in hospitality.
Dave’s Hot Chicken, which Azzurri won the UK and Irelandmaster franchise rights for in 2024 and has franchise rights for in 10 other countries, has been a growth driver for Azzurri, which recorded flat revenue figures of £303.1m for the year to 30 June 2025.
Azzurri’s franchise agreement is to roll out a minimum of 180 Dave’s Hot Chicken restaurants across Europe, with around 14 expected to be in the UK and Ireland by the end of 2026.
Avoiding retail legacy tech entanglement
Hingston says the brand, which is essentially a startup in terms of its European status, gives his group’s tech team a chance to pull new growth levers and avoid getting in a legacy tech tangle often associated with more established businesses.
“It’s never totally greenfield, there are always a few shrubs and weeds you’ve got to get through, but it’s such a great opportunity,” Hingston says of the brand and its modern tech stack.
Work done with Dave’s could then provide a tech blueprint for its group stablemates such as ASK and Zizzi, which, like any restaurant chains, require continual upgrading and reinforcement from a tech and digital perspective. “If I have tech and I’ve proved I can scale it, [the question becomes about] applying it back into the rest of the group,” Hingston adds.
Whether the opportunity for modern tech development and transformational change ultimately sits with Azzurri remains to be seen, however, after Bloomberg reported on 12 March that the restaurant group was considering the sale of Dave’s.
Either way, the internal positivity about the brand and the seemingly external interest in it highlights the potential for the business as it continues to grow out from its Los Angeles roots.
“In Dave’s, we have a great opportunity of a new, successful, high-volume quick service business where you can use tech to give you a real advantage, where you can grow a business a lot quicker,” Hingston says.
How might that tech or digital capability present itself? First – and an area Azzurri is particularly excited about – is in dynamic pricing.
As reported, the group incubated and spun out Openr, a tech and data platform that enables speedier menu changes and price elasticity. That now-standalone tech business, which was the brainchild of Hingston’s former boss Joel Robinson, who continues to run the operation, is still used by Azzurri Group.
Travel and retail have done [price optimisation] for years, but you can’t do it if it takes you six weeks to update a price or you have set systems Jim Hingston, Dave’s Hot Chicken
Being able to change pricing per location, time of day or based on special events is seen as a key way tech can be a business driver. Think special offers at typically quieter times of the day to draw customers in, or more premium prices in line with demand – there are so many ways this technique can be business positive, Hingston says.
Legacy tech issues, he adds, mean it can take six months to conduct a menu change, or six weeks to update pricing in the hospitality space. “Retail peers look at me as if I’m on a different planet,” he says. “As an operator, we’re looking at pricing optimisation. Travel and retail have done it for years, but you can’t do price optimisation if it takes you six weeks to update a price or you have set systems.”
The ideal tech infrastructure Hingston and his team – which comprises around 25 roles and includes a relatively new in-house engineering team – are keen to implement, starting with Dave’s, is a headless digital architecture. They want to build a “tech ecosystem” around some of those principles of price optimisation.
Openr is being already being used by the group via partnerships with aggregator platforms Deliveroo, JustEat and UberEats.
Making physical stores an ‘event’ for digital natives
Elsewhere from a tech perspective, Hingston envisages opportunities for Dave’s to create interactive experiences for its restaurant customers via the digital screens deployed at venues.
The screens it has installed in its flagship London Shaftsbury Avenue site replicate the nearby Piccadilly Circus billboards. The tech boss, who joined from Gym Group in 2024, describes the need to bring excitement to life in store “so it feels like an event”.
This is an area of particular focus for Dave’s, which has a core influencer-led, digital native and social media-loving Gen Z audience. In terms of capturing their hearts and minds, one mooted idea is to use the digital billboards in restaurants – already in place to facilitate the Openr-enabled dynamic pricing – to gamify the customer experience (CX). Trison, which provides the screens, can enable loyalty app-linkups that permit users to control some of the content on display.
“That’s expensive tech but we’re seeing the cost come down and there are so many fun things you can do with an in-store experience when you have a digitally native audience,” Hingston says.
Around 10-15% of in-restaurant interactions at Azzurri Group are conducted via the order-and-pay system facilitated on smartphones, but generally speaking Hingston believes the best tech in hospitality and the wider retail landscape is hidden. The tech that powers operations rather than any shiny hardware and software that can bring friction to the CX is most crucial, he acknowledges.
For example, Wi-Fi usage in Dave’s is considerably higher than that encountered in the more family-oriented and traditional ASK branches, according to the digital boss. That shows the importance of network infrastructure in modern hospitality.
AI a useful tool, but cannot replace creativity
On the artificial intelligence (AI) revolution sweeping across retail and consumer-facing industries, Hingston is keen for his peers and the leadership team to experiment to see what business benefits may arise from it.
“I’m in the background making it safe – you must make sure you have good guardrails in place and know the limitations,” he says.
I think about the craft of software development; there is part of it which is artistry and deeply creative, and AI isn’t going to be able replace that Jim Hingston, Dave’s Hot Chicken
Hingston is cautious about overuse and over reliance on AI, though: “I think about the craft of software development; there is part of it which is artistry and deeply creative, and AI isn’t going to be able replace that – we need to temper things a little bit. But what’s great now is that, because the cost to entry is often a lot lower, I’m innovating quicker.
“Tech has a reputation of burning through cash, late deliveries and projects that are never ending – now you can break things down more easily. My team remind me we’re probably doing treble the amount we were as tech department.”
At Azzurri Group, there are six major tech programmes under way, Hingston says – “some deeply transformational”, adding: “Normally you do one or two of those a year. The team’s not much bigger and we’re spending less.”
It appears there are opportunities galore at Azzurri, and in particular at Dave’s Hot Chicken. Whether it remains a part of the group or not in the months to come remains to be seen – clearly, there’s plenty for the hospitality tech panel at Retail Technology Show to discuss at London’s Excel on 22 April.
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