Cisco today unveiled a prototype switch it says will significantly accelerate the timeline for practical, distributed, quantum-computing-based networks.

Cisco’s Universal Quantum Switch is designed to connect quantum systems from different vendors, such as IBM, IonQ, Google and Rigetti, in all major qubit encoding technologies, at room temperature, and over standard telecom fiber, according to Vijoy Pandey, senior vice president and general manager of Outshift, Cisco’s emerging technologies and incubation group.

“Today we have quantum computers operating at roughly 100 to 1,000 qubits in size, and from the public roadmaps of leading quantum players, we believe this number [is] going up to 10,000 in the next three years,” Pandey said. “Actual quantum computers will get bigger over time, of course, but it creates a big scalability problem once you start connecting them. What the switch will do is effectively link smaller quantum computers and create a large, distributed quantum computer, allowing faster scaling than building one massive quantum computer alone.”

“This is a foundational piece of technology that lets us move from direct point-to-point connections, the tin cans and a wire, to building out a quantum network, to building out the quantum Internet at scale, to be able to connect those quantum computers at scale within the data center, but also to be able to connect quantum sensors across the Internet at scale as well,” Pandey said.

The Cisco Universal Quantum Switch works in many of the ways that current multivendor switches work to form the backbone of the internet in that it allows connectivity no matter what the underlaying protocols and equipment are, Pandey said. When two quantum computers need to share information, the Universal Quantum Switch accepts the signal in whatever modality it arrives, translates it into a common language for routing, and delivers it in the format the receiving system needs, without losing any quantum information along the way, Pandey said. 

The switch preserved quantum information with less than 4% degradation in encoding and entanglement fidelity in proof-of-concept experiments, Pandey said.

This is made possible by a Cisco-patented conversion engine, where output modality can match the input or be an entirely different one, letting the quantum switch connect and translate between quantum systems that were never designed to talk to each other. It’s a critical capability for building quantum networks that work across different vendors and technologies, according to Cisco.

“The switch is non-blocking, allowing multiple photons to flow through the chip at the same time, each independently routed while preserving its quantum state, enabling flexible scalable quantum networking,” Pandey said.

The major quantum encoding modalities which are used to carry quantum information include:

• Polarization (the orientation of light waves)
• Time-bin (the timing of light pulses)
• Frequency-bin (the color or frequency of light)
• Path (the physical or spatial path)

To date, the quantum switch has been experimentally validated with polarization encoding. Support for time-bin and frequency-bin is built into the switch design and will be the next step in Cisco’s ongoing validation process, Pandey said.

The switch can also be used to tie together and process data from quantum-sensing devices which are or will be used in applications from healthcare and navigation to energy and infrastructure.

The Cisco Universal Quantum Switch is just the latest component in the vendor’s quantum arsenal which is aimed at offering a full stack of data center-oriented quantum technologies. 

In September the vendor rolled out a package of prototype software it says will facilitate distributed quantum computing networks and support real-time applications. The software stack includes three layers: an application layer with a network-aware distributed quantum computing compiler that supports quantum algorithm execution in a networked quantum data center; a control layer with quantum networking protocols and algorithms that support the applications as well as manage the devices (hardware and software) that make up a quantum network through northbound and southbound APIs; and a third layer for device support, consisting of an SDK and APIs to physical devices as well as a library of emulated and simulated ones.

The Universal Switch is based on the quantum entanglement chip announced by Outshift last May that generates pairs of entangled photons that can instantly transmit quantum state between each other, regardless of the distance between them. The entanglement chip generates 200 million entangled pairs per second. The chip operates at room temperature, uses minimal power, and functions using existing telecom frequencies. It’s designed to work with existing infrastructure, meaning it can send photons over existing fiber. And it operates at standard telecom frequencies, so there’s no need to rip and replace anything to support it, according to Cisco. In addition, because of these properties, customers could deploy gear supporting the chip alongside an existing classical computer infrastructure, Cisco said.

“The quantum future won’t be built by any one company or any one technology. It will be built by connecting them all with this technology,” Pandey said.