Vanita Srinivasa was the first professor at the University of Rhode Island to work in quantum information science. This powerful new realm of technology could redefine how we use our devices.
In traditional computers, information takes the form of binary “bits,” which can only carry the value of zero or one. In quantum computers, however, quantum bits, or “qubits,” can store the values of zero, one, or a combination of both, allowing for exponentially faster calculations of data.
Srinivasa, assistant professor of physics and founding director of the Quantum Information Science program at URI, led a team of physicists —including Jacob M. Taylor of the University of Maryland and Jason R. Petta of the University of California, Los Angeles, to lay out research that shows how to link qubits over long distances to enable them to work together to perform quantum operations. This research brings physicists a step closer to successfully developing a quantum computer, which they say will be transformative for computing technology.
Q: What does your research say about the future of quantum computing?
Srinivasa: In order to have a quantum computer, you need to have both individual control of each quantum bit and the ability to link them so that they can perform calculations in a correlated way. That correlation is what doesn’t exist in classical computers. But as you add more and more qubits to attempt to correlate them, it becomes very, very complicated. To reach the hundreds of thousands or even millions of qubits that you need for a full-fledged quantum computer, you need to have a more flexible system. Our paper lays out a step-by-step method for actually doing that, showing how you can actually add a few qubits and link them with long-range links and build them up like LEGO blocks in order to build up the quantum computer.
What inspired this work?
The inspiration came from [Dr. Petta’s] experiments where he was essentially having this challenge of, how can we go beyond two [qubits] if we really want to use this kind of system to build up a quantum computer that can do something useful. And so we started to think about how we can actually make this system flexible. Different physical platforms for quantum computing have different advantages … Essentially, we were thinking about what we could do to make the device more flexible. We had to go back and revise the theory and eventually, we came up with this nice, systematic picture of how you can introduce this flexibility.
What real world applications can this technology lead to?
Some of the things that we know are possible is secure communication. If, for example, you want to send a message from one person to another, and you want to do that in a secure way, you can’t do that if you have a telephone line or something that can be tapped or somebody can eavesdrop on the line. With quantum entanglement, the kind of thing that we’re actually talking about in the paper, you can have a protocol for sending a message from one party to another where, if somebody eavesdrops, quantum mechanics says that if you measure that or if you try to read that state, then it will change. So if one person sends a message to another person, they will know if the message ends up being changed.
There’s also the fact that we can design more secure ways of encrypting information, and in some sense, we have to, because all of our credit card numbers are encrypted right now in conventional ways, basically by multiplying one large number, and relying on the fact that no current computer can factor that number.
What are the next steps for applying this research?
We have this method, but in order to actually implement it in a real device, we need to do more to actually understand the way it works. There is work to be done on the theory side, but also our third co-author, [Petta], has been making these kinds of devices where you can link semiconductor spin qubits over long distances. He’s had the first demonstration in the world of that kind of linkage in a silicon chip, which is the same material we use for conventional computer chips. Our next steps would be to take what we’ve done in this first work and apply it to [Petta’s] devices. I hope to get students and postdocs at URI involved in that as well.
What should people know about these discoveries?
Quantum computing itself has potential that we have yet to discover. It has many uses that we know about in principle, but it has many more uses that we haven’t discovered yet. Those uses have the potential to revolutionize almost everything that we’re doing now. It’s a central technology that everybody, if they don’t know about it now, they will know about it to some extent at some point.
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