Cisco shows Universal Quantum Switch prototype to connect quantum systems

• Cisco Universal Quantum Switch connects different quantum systems.
• The switch routes quantum signals over telecom fibre without measuring them.

Cisco has shown a working research prototype of a switching chip designed to connect different types of quantum computers and quantum sensors over a shared network.

The company said the Cisco Universal Quantum Switch can route entangled photons while preserving their quantum state. The switch is designed to operate at room temperature, use telecom frequencies, and run over standard telecom fibre.

Cisco focuses on quantum networking

Cisco is developing quantum networking technology rather than its own quantum processor, focusing on the networking layer for connecting systems built with different technologies.

Quantum computers are currently being built using several techniques. Some systems use atoms suspended in a vacuum and controlled with lasers, while others use superconducting circuits cooled close to absolute zero.

Vijoy Pandey, senior vice president and general manager of Outshift, Cisco’s emerging technologies and incubation group, said researchers expect different quantum computing approaches to retain specific strengths. Cisco’s switch is intended to translate between those systems so they can communicate through one network.

How the switch handles different quantum systems

Quantum systems do not all encode and transmit information in the same way. Cisco said the switch supports four major quantum encoding methods: polarisation, time-bin, frequency-bin, and path.

Cisco said the switch uses a patented conversion engine to translate quantum signals between encoding formats at input and output. The output format can match the input format or use a different one, depending on the receiving system.

Cisco said the prototype has been experimentally validated with polarisation encoding. Support for time-bin and frequency-bin encoding is built into the design and remains part of the company’s ongoing validation work.

The company said the switch does not measure the quantum state during routing, because measuring a quantum signal would collapse it.

Cisco said the prototype addresses a scaling problem in quantum networking. A fully connected 1,000-node system using point-to-point links would require about 500,000 direct connections, according to the company.

Point-to-point designs become harder to manage as more devices are added. Each direct connection requires dedicated fibre and supporting components, which increases physical complexity and limits how easily a quantum network can be expanded.

A switching layer would reduce the need for direct fibre links between every pair of devices. Cisco said this would allow quantum computers and sensors with different architectures to be connected through shared infrastructure.

The company also said the switch could allow shared use of costly network components, including single-photon detectors and entanglement sources. These specialised components are used to create and detect quantum signals, and Cisco said a switch-based design would allow them to be shared across a network instead of being tied to individual links.

Cisco described the prototype as being built for data centre conditions. It operates at room temperature, removing the need for cryogenic cooling at the switching layer, and uses existing fibre infrastructure associated with telecom networks.

Testing and performance results

Cisco said its researchers tested the prototype using the company’s own entanglement source and single-photon detectors. In proof-of-concept experiments, the company said the switch showed average degradation of 4% or less in quantum state fidelity and entanglement.

The company also reported sub-nanosecond electro-optic switching, with connections reconfigured in as little as one nanosecond. Cisco said the prototype consumes less than 1 milliwatt of power.

Cisco did not announce a commercial release date for the switch.

Security uses under development

Cisco is also exploring nearer-term uses while large quantum computer networks remain under development. One research prototype, Quantum Alert, is being developed to detect eavesdropping on existing fibre networks by monitoring whether entangled photon pairs remain intact.

Under that approach, interception of the signal would collapse the entanglement and trigger an alert. Jeetu Patel, Cisco’s president and chief product officer, said quantum sensors connected through the switch could help detect network eavesdropping.

Cisco is also researching Quantum Sync, which it described as a method for correlated decision-making across distributed locations. Both Quantum Alert and Quantum Sync remain research prototypes.

Cisco executives said large networks of quantum computers are not expected until the 2030s. The company said security applications using quantum sensors could emerge earlier because such sensors are already available.

Part of a wider quantum stack

The switch is part of Cisco Quantum Labs’ quantum networking work, which covers chips, protocols, software, and applications.

Cisco said that portfolio also includes a quantum network entanglement chip and a network-aware Quantum Compiler. The entanglement chip is designed to generate entangled photons, while the compiler is intended to manage how quantum algorithms are distributed across multiple quantum processors.

Cisco said the switch, entanglement chip, and Quantum Compiler were developed at its quantum labs in Santa Monica.

Cisco is also working with companies including IBMQunnect, and Atom Computing. The company said those collaborations are tied to interoperability work, rather than the development of a single quantum computing architecture.

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