14 DAY TRIAL // The Random Access Memory modules inside a typical personal computer are amongst the most energy consuming devices while working. A Quantum Random Access Memory on the other hand, would not only bring advancements in terms of quantum computing but could also be applied to classical computing to create low-energy quantum access memories. Some researchers believe that a QRAM architecture could spawn the appearance of an anonymous Internet search, or a quantum Internet search if you may.
"My colleagues and I were interested in protocols for quantum Internet search. And we were also interested in what we could do with even a rudimentary quantum Internet. But first you have to develop this quantum RAM", says MIT researcher Seth Lloyd.
Along with Vittorio Giovannetti from NEST-CNR-INFM and Lorenzo Maccone from the University of Pavia, Lloyd developed a system that would work as a Quantum Random Access Memory. "Our design is based on a bucket brigade soft of design. There is just too much decoherence in classical RAM architecture. Too much for the quantum states to remain intact", Lloyd says while explaining how the team got the QRAM to work on a classic RAM design.
"Let's say you have a gigabyte of RAM. That means you have one billion memory slots, each with an address. When you want to access one, and address is given, let's say it is about 30 bits long. The first bit will throw two switches, the next will throw four, and so on until a billion switches are thrown at once. The conventional design is incredibly wasteful. And it is susceptible to noise and interference. We saw that this wasn't going to work at all in terms of quantum RAM", said Lloyd.
"It is a sneakier way to access RAM. In the same gigabyte RAM, we send the first bit of the address along a path. Once the first layer is accessed, the next bit comes, following the path of the first bit, until it reaches the second layer. The third bit then traces the two paths before it. In this way, all the bits of the address only interact with two switches", he said.
The thing is that although the QRAM is very energy efficient, it is not fast enough as compared to the classic RAM. "You'd have to be willing to make that trade-off. If you had a quantum Internet, then this would be useful. This offers a huge decrease in energy use and an increase in robustness", giving people the possibility of conducting completely anonymous Internet searches.
Nonetheless, implementing the system could take a while. "We're working on setting up an experiment with optics to show how this would work. For a quantum Internet to work, we need what is called dark fiber. In some places, this is already being used for classical communications. But we would need more of it, and the necessary quantum switching structure is only just now being developed", Lloyd explains.