The dream at Hitachi-Cambridge Laboratory is to create a scalable quantum computer on a classical interface. They refer to this technological approach as “Spin Qubits in Silicon Transistors”. Although the technology is at a nascent stage it could overtake other approaches.
The quantum computing community is channeling its efforts towards building the ultimate machine: a digital quantum computer that tolerates noise and errors that could be applied to any problem in machine learning, quantum chemistry, material science, optimisation and sampling.
However, this is a road that is long and arduous. The general consensus is that a universal quantum computer is at least a decade away. In this time there will need to be some serious gains in hardware and software. Success is dependant on how effective the collaborative work is between industry and academia.
Today there are a huge number of academic and industrial labs committed to overcoming the technical hurdles in the field. Scientific and engineering approaches to quantum computing vary enormously and there are no established winners. Generally speaking there are three broad road maps to create a universal quantum computer and currently there is not even a consensus on the best material to construct the future machine. Some labs are working with atoms, others novel particles, others are looking in to light particles (photons), and finally some use superconductors and semiconductor devices.
For the start of our April innovators series we wanted to explore a potentially revolutionary approach in the field of quantum computing. The major discovery that came out of the Hitachi Cambridge Laboratory has been in the area of Spintronics : This focuses on the spin of electronics instead of the charge of electrons to obtain functionality in electronic devices.
Spintronics combines superconducting materials – which can carry a current without losing energy as heat – with spintronic devices. These are devices which manipulate a feature of electrons known as their “spin”, and are capable of processing large amounts of information very quickly. Future devises could pave the way for a new generation of ultra-low power supercomputers, capable of processing vast amounts of data, but at a fraction of the huge energy consumption of comparable facilities today.
The Hitachi-Cambridge Laboratory are now looking at creating an architecture for a silicon-based quantum computer processor based entirely on complementary metal-oxide-semiconductor (CMOS) technology. We wanted to find out what this means and explore the network of academic institutions venturing down this road. We also sought to illuminate new insights into the future of quantum computing applications for industry.
At the end of March, Quantum Business spoke with Fernando González Zalba, Senior Research Scientistat the Hitachi Cambridge Laboratory . Fernando joined Hitachi in 2012 after the completion of a PhD in Single-Atom Electronics at the University of Cambridge. His role today is part of the research and development group in Hitachi Europe and also part of Hitachi’s centre of exploratory research.
“My main area of research is quantum information processing. One of the reasons why the world wants to develop a quantum computer is to solve problems that you will never be able to solve with a classical computer. This is a much more efficient way of computing or solving problems – eventually this leads to more efficient energy solutions to problem solving.”
“Spin Qubits in Silicon”
Fernando tells me that today he is leading the effort on Silicon CMOS architecture for a spin-based quantum computer. Complementary metal–oxide–semiconductor, abbreviated as CMOS is a technology for constructing integrated circuits in classical computers. CMOS technology is the basis for all modern processor chips and is used in microprocessors, micro controllers, static RAM, and other digital logic circuits.
“This is the technology that we want to use to make a scalable quantum computer”
“So the latest thing we are doing in the space is a project that was funded in 2016 called MOS-QUITO. When you break it down it stands for Metal-Oxide Semiconductor Quantum Technologies. It is a European project that aims to demonstrate that you can have a spin qubit made from the very same technology that is used to create microprocessors. This project is in collaboration with several European institutions.”
This approach to the field is much more noble in the sense that it is more recent than other technological approaches. “The first spin qubit in silicon was demonstrated only in 2012 and the circuits that the field can produce at the moment are much simpler than other technologies, but we are likely to see results.”
However, our goal at the Hitachi Cambridge Lab is that over the next 10 years we should be able to produce a circuit of around 50 qubits. This will allow us to start tackling problems that cannot be done with classical computers.”
“Although there is no single discovery that has become a successful product yet, the team are on the cusp of something that could have profound implications. In our case what we aim to demonstrate is a quantum computer that basis its functionality on the spin of a single electron in silicon devices. There is a very clear link between the field of spintronics and the implementation of the type of qubit that we are trying to develop, a spin qubit in silicon.”
Why Is This Appealing?
One of the most significant challenges that the quantum community is attempting to overcome is the fact that quantum machines require extensive error-correction to make up for the fact that qubits are inherently fragile. They can only remain in their quantum state for a tiny amount of time and are exceptionally difficult to read without interfering with the results. Fernando claims that the Hitachi-Cambridge team are confronting this challenge head on.
“If you write the quantum information on the spin of a single electron it can last for a very long period of time. Much longer than any other solid state implementation. This is one of the major advantages of using spins in silicon.”
“We’ve been doing big experiments over the last few months that were quite successful. The first one is related to how we read the quantum information. For a quantum computer you need exactly the same concepts as you need for a classical computer to work. The first is to be able to write the information and store it in a system for a certain amount of time. You need to be able to do operations on it but afterwards read the results and information you have in the system.”
“In quantum computers you need a method to read the quantum information. There are many different ways to do this in classical information and there are also different ways in quantum information. What we’ve recently reported is that we’ve come up with a new method to read the quantum information of spin qubits in silicon or in semi- conductor devices that is the most sensitive method that has been demonstrated up to date.”
“The other great achievement that we recently announced is related to the fact that we use silicon technology used in microprocessors. What we have reported is that we can create circuits that combine qubits, with digital electronics, and all on the same chip. This is great because in the future you could imagine you will get answers from your quantum processor and these will have to be processed by a normal computer. If you can integrate your quantum part of the computer with the classical part in the same chip, you could enhance the performance of this hybrid-like processor because you will reduce the time it takes to transfer information between two distinct systems.”
The Hitachi Network
“Hitachi is open to collaboration with academic institutions. This is a top priority – to establish a strong collaboration with key players in research.”
The Hitachi Cambridge collaboration is emblematic of how successful the bridge between industry and academia can be. When the two work effectively they share a symbiotic relationship. Academia produces graduates who are absorbed by industry. Research work in universities are taken up by the industry and turned into products and services that can be pushed into the commercial sphere.
“There is a very strong collaboration between the Hitachi Limited and the University of Cambridge . The lab itself is embedded in the department of physics at the university. Our offices and labs are in the same building as the department of physics. This collaboration started 30 years ago. In my knowledge it was the first situation in which a large corporation decided to embed a research centre into a university. This is also one of the first examples of a Japanese corporation embedding a lab into an institution.”
“Our focus has been on fundamental physics of electronic devices. The Cambridge Laboratory is a fundamental research lab. It is looking into technologies that may become useable for society in a time scale of 10 years or longer.”
“This is what the University of Cambridge has been famous for around the world. For fundamental discoveries that have led to successful technologies. The partnership has always been very fruitful.”
The MOS-QUITO European Project
Hitachi also has a large consortium of academic partnerships across Europe with different institutions developing quantum technology. “Hitachi is open to collaboration with academic institutions”, Fernando reveals. “Whenever we have the opportunity to alliance in areas of our research we apply to the European Commission with partnership with institutions in Europe – not only industrial ones but also academic ones.”
The MOS-QUITO project aims to demonstrate that you can have a spin qubit made from the very same technology used to create microprocessors. “This project is in collaboration with several European institutions, including the University of Copenhagen, University College London, CNR in Milan, CEA-Leti in France, Ecole Polytechnique de Laussane and there is another partner in Finland, a national institution for nano fabrication called VTT.”
Quantum Powered Simulation
The next part of our conversation covered the use cases of quantum computing. Fernando claims that this is the most promising area for industry.
One of the main applications for quantum computing is in the simulation of molecules. Chemistry, medicine, energy, materials and manufacturing are the verticals most likely to see the most rapid change over the next 5 years. Future quantum computers could enable you to design new chemicals and drugs for fighting diseases like cancer and even design new materials for more energy efficient buildings.
Fernando believes that a small number of qubits and a simple processor with 50 – 1oo qubits – would enable you to start tackling this problem soon.
“I think this is the greatest promise of quantum computing. They will be much much more efficient than classical computers in simulating quantum systems. When we talk about the simplest molecules and even with the most powerful classical simulators we are not 100 per cent accurate on obtaining the experimental values of the data in the laboratory. By moving to a processing system that is purely quantum mechanical – which is what these molecules are – we can obtain much more accurate descriptions of the behaviour of simple molecules.”
Fernando points to the example of the ammonium molecule (NH3). “This very simple molecule is used in fertilisers and is one of the main reasons why we are able to produce so much food and feed a good part of the population. The problem is that to produce this very simple molecule it takes almost 5 per cent of the world’s energy. The reason for this is that we need to use very high pressures and very high temperatures that cost huge amounts of energy.”
“What we have discovered is that bacteria in nature can synthesise this molecule from its constituents with much less energy. They don’t need to heat up or apply very high pressure; they can do it naturally almost in standard conditions. So there is a way of producing this molecule in a much more efficient way that will save lots of energy. We don’t know how to do it yet. But I think a quantum computer will definitely allow us to study this system better and maybe figure out a way to synthesise this molecule with much less energy.”
Ultimately this insight from Fernando González Zalba and the perspective of Hitachi-Cambridge is yet another welcome voice to the growing network of quantum computing experts connecting with Quantum Business every week. Keep your eyes open for ‘Spin Qubits in Silicon’!
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Article written by Hal Briggs from Quantum Business