Photonic executed a teleported CNOT gate between physically separated silicon spin qubits, thus satisfying the first requirement of long-distance quantum communication.

An artist's rendition of interconnected qubits

In November 2023, Microsoft and Photonic initiated their collaborative effort to advance quantum networking and computing. Today, Photonic announced the capability to successfully transfer quantum information between two physically separated qubits in a point-to-point connection using photons at telecom wavelengths. In a span of only six months, Photonic was able to achieve this significant scientific milestone on the path to a quantum internet, thereby accomplishing the first of our three collaborative goals and putting theory into practice. Notably, this accomplishment demonstrates that existing telecommunication networks have the potential to enable long-distance quantum communications—the foundation for a quantum internet and distributed quantum computing. 

This milestone extends the boundaries of quantum computing beyond isolated systems. Effective execution of large-scale quantum algorithms across multiple quantum computers relies heavily on vast amounts of distributed entanglement. Our work with Microsoft and these recent demonstrations emphasize the promise of our unique architectural strategy in addressing the challenge of scaling beyond individual nodes. Despite the significant work that remains, recognizing the critical role of entanglement distribution in the development of scalable quantum technologies is essential.” 

—Dr. Stephanie Simmons, Founder and Chief Quantum Officer of Photonic, and the Co-Chair of Canada’s National Quantum Strategy Advisory Council 
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Photonic’s spin-photon architecture 

Quantum computing uses qubits, or quantum bits, to store and process information. There are multiple types of qubits, one of which is a silicon spin qubit. Photonic’s architecture combines the information-storage and information-processing capabilities of silicon spin qubits with the information-transmission capabilities of photons in a spin-photon interface that can be used for quantum networking and quantum computing. This novel architecture supports quantum communication by operating natively in the O-band of telecom wavelengths, giving it the potential to scale globally by using existing telecom fibers.  

Photonic's chip that houses the silicon spin qubits.
Photonic’s chip that houses the silicon spin qubits.

Quantum logic gates 

Both classical and quantum computers perform operations with logic gates that convert input data into outputs. One type of quantum logic gate is a controlled NOT (CNOT) gate, which operates on two qubits—a control qubit and a target qubit. If the state of the control qubit is 0, then the state of the target qubit remains unchanged. However, when the control qubit’s state is 1, the state of the target qubit is flipped, so that 0 becomes 1, or 1 becomes 0. To perform quantum computation on a large system, logic gates like the CNOT must be implemented within and between modules. As a prerequisite to scalable, long-distance quantum computation, the distribution of entanglement to physically separated quantum systems—known as distributed entanglement—must be achieved. 

Distributed quantum entanglement 

Through a collaboration with Microsoft, Photonic achieved distributed entanglement between silicon spin qubits housed in separate cryostats, connected by a 40-meter fiber-optic cable. In a sequence of three demonstrations, each building upon the success of the last, the Photonic team: 

  1. Verified that the photons transmitting the quantum information through the fiber were indistinguishable from one another.
  2. Successfully entangled the qubits with these photons.
  3. Executed a remote quantum logic gate sequence—for a teleported CNOT gate—between physically separated qubits.   

This accomplishment showcases the capability to operate a quantum computer in an industrial setting by using teleportation to execute logic gates between qubits in different locations. Entanglement between qubits that are not connected physically, or even located in the same cryostat, paves the way for long-distance communication between quantum computers and is one means to accomplish scaled quantum computing. Potential applications of this technology include securely distributing keys for encrypted data communication and enabling reliable, long-distance quantum networks. This animation demonstrates how the team at Photonic achieved distributed quantum entanglement:

Photonic's achievement

Distributed quantum entanglement

diagram

Quantum networking is not intended to replace classical networks—rather, it will expand their capabilities so that quantum information can be transmitted between quantum or classical endpoints. Now that we have entered Stage 1 of quantum networking, defined as achieving entanglement between two separate quantum devices in a point-to-point connection, the next step is to improve the quality of the entanglement distribution. After doing so, we will work toward entangling additional quantum devices, the achievement of which will mark entry into Stage 2. Ultimately, we aim to achieve Stage 3, which is when long-distance quantum communication will enable a quantum internet.  

A description of the three stages of quantum networking. Stage one is defined as point-to-point, in which entanglement is delivered between two separate quantum devices. Stage two is defined as many-to-one, in which connections are made between sites. Stage three is a quantum internet, which enables long-distance quantum communication.

Integrating Photonic’s architecture into Microsoft Azure 

Microsoft and Photonic will continue their collaboration and work toward integrating quantum-networking capabilities into everyday operating environments through the global infrastructure of the Microsoft Azure cloud. In addition to having applications in quantum networking, Photonic’s architecture is equally applicable to distributed quantum computing. We intend to provide customers of Azure Quantum Elements with an opportunity to access Photonic’s hardware when available, unlocking the potential to solve complex scientific problems.  

By working together, Microsoft and Photonic are bringing their shared vision—creating and scaling systems that can help solve issues affecting all of humanity—closer to reality. At Microsoft, we are incorporating quantum technologies, as they arise, into our existing cloud high-performance computers to create hybrid systems that—along with the power of AI—have the potential to help scientists create more sustainable products, discover new therapeutics, and more. 

Advances in AI and quantum computing have the potential to help researchers solve global scientific challenges. To advance the safe use of these technologies, we will ensure that they are developed and deployed responsibly. We will continue to adopt thoughtful safeguards, building on our commitments to responsible AI and embracing responsible computing practices as these capabilities grow.

Learn more about Photonic’s achievement and how Microsoft intends to apply it