Microsoft's cool quantum computing plan embraces cryogenic memory

Microsoft and Rambus say standard DRAM won't cut it for the superfast quantum computers of the future.

Microsoft and Rambus are working on cryogenic memory for quantum computers.
Credit: Julian Kelly/Google

Microsoft has crazy quantum computing plans: first, it built hardware based on a particle that hasn't even been discovered. Now, it's hoping to co-design super-cool memory for quantum computers.

The company is working with Rambus to develop and build prototype computers with memory subsystems that can be cooled at cryogenic temperatures, typically below minus 180 degrees Celsius or minus 292 degrees Fahrenheit.

Cryogenics goes hand in hand with quantum computers, which promise to be significantly faster than today's PCs and servers and may even eventually replace them . But the systems are notoriously unstable and need to be stored in refrigerators for faster and secure operation. As an example, D-Wave's 2000Q quantum computer needs to be kept significantly cooler than supercomputers so operations don't break down.

The idea of cryogenic memory was first explored in 1991, but Rambus and Microsoft are improving on the concept with modern technologies. The two companies started collaborating on research of cryogenic memory in late 2015. Now, they plan to build prototype systems with the memory, though no release date has been announced.

Microsoft is also aggressively pursuing quantum computer hardware and software, and late last year, it recruited some of the top researchers in the field. The company is also developing an advanced software toolkit to run with the quantum computer. But Microsoft's quantum computing system is based on a new topology, exotic materials, and an undiscovered particle, and it could be years or even decades before it is released. Rambus, meanwhile, is known for developing memory technology and then licensing it.

Memory that can keep up with a quantum computer

A quantum computer will need a corresponding improvement in memory performance, and cryogenic memory could be the answer.

Cryogenic memory is being proposed as a possible replacement for existing memory technologies like DDR DRAM. It's becoming hard to make smaller memory chips with more capacity using current technologies. Servers are being loaded with more memory to run applications like machine learning and analytics, and a small box of cryogenic memory could replace large arrays of space-hogging DRAM.

Cryogenic memory is also being developed for supercomputers. Like quantum computers, cryogenic memory blocks will be faster and more efficient at cooler temperatures in data centers, the companies say. Supercomputers and discrete cryogenic boxes could be linked via high-speed interconnects.

All that performance will come at a price, however. Refrigerators for quantum computers and cryogenic memory will result in large electric bills. Supercomputers running on standard fan-based or liquid cooling could use cryogenic memory operating at lower temperatures, but adoption will depend on the price of converting to the new memory.  

Microsoft's not the only game in town, though. IBM and D-Wave are already chasing other types of quantum computers. The D-Wave 2000Q is based on quantum annealing, which is considered an easy and practical way to build a quantum computer but is useful only for specialized enterprise applications. IBM's 5-bit quantum computer, meanwhile, is based on the so-called gate model, which is more complex but another way to achieve a universal quantum computer.

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