Researchers have created a scalable quantum computing platform that has been shrunk down to the size of a penny, which would serve as the basis for a quantum computer that can achieve quantum speeds while using far fewer devices than current designs. 

The team hopes their research, published in Nature Communications, will help push quantum computing forward in the constant pursuit of use in real-world applications. 

Over the past few years, quantum computing has gone from science fiction to a realistic technology that may see use in the next few decades. While quantum teleportation and even quantum computer chips have been demonstrated previously, the technology is still a long way off seeing real-world use.  

The idea behind quantum computing is relatively simple. Conventional computers process information and communicate through bits, which exist in binary: they are either zero or one. Quantum computers process information in qubits, which can be zero, one, or both at the same time. Except, why stop there – they also utilize quantum modes (called qumodes), using all the variables between zero to one. 

Another benefit of quantum computers is they do not necessarily perform actions in a sequence like conventional computers. For example, if you wanted to know how many factors the number 600 has, a current computer would systematically go through each number and see if it can multiply into 600. A quantum computer would do every number at the same time. 

To do so, it needs to be able to create vast amounts of qumodes. In their new paper, Xu Yi and colleagues from the University of Virginia employed the use of light, a field known as quantum photonics. Much like an optical fibre, quantum photonics uses multiplexing of the full spectrum of light to carry information, with each wave of light potentially becoming a quantum unit.  

The team created a device called a microcomb, which converts photons of light from single to multiple wavelengths. These photons are sent around a ring, which builds up optical power (the amount of energy per unit time within the device) and increases the likelihood the photons will interact with one another, creating quantum entanglement.  

They placed the device on a small chip, much like a standard computer chip, and were able to generate 40 qumodes from a single device – although they believe there were likely more generated that were not picked up by the measuring equipment. Yi and the team believe that by using multiplexing nodes in quantum computers and optimizing the equipment, they will be able to generate far more than 40. 

“We estimate that when we optimize the system, we can generate thousands of qumodes from a single device,” Yi said in a statement. 

While the device still produces just a fraction of the required processing power that a real-life quantum computer would require, it offers distinct advantages over other quantum systems. Firstly, one of the largest challenges in creating a scalable quantum computer is that many systems require cryogenic temperatures to operate, using vast amounts of energy, complex cooling systems, and limited applicability to most real-life use cases. Photonic systems are able to run at room temperature. Yi also states that as the chip used relatively standard fabrication techniques, it could be mass-produced easily.