- Quantum Internet
- Also: quantum network protocol
- Also: entanglement protocol
Quantum Internet Protocol
A standardized procedure for distributing entanglement, performing quantum teleportation, or transmitting quantum states across a network of quantum nodes, analogous to TCP/IP for classical networks but fundamentally different due to the no-cloning theorem.
The classical internet runs on protocols: agreed-upon rules for how data is formatted, addressed, routed, and delivered. Building a quantum internet requires an analogous stack of protocols, but nearly every assumption that underlies TCP/IP breaks down in the quantum setting. Designing quantum internet protocols means starting from different physical primitives and working upward.
Why classical internet protocols don’t work
Classical internet protocols are built on a foundation of copying. A packet travels from source to destination by being copied at each router: the router reads the destination address, makes a forwarding decision, and retransmits a copy of the packet. Packets can be stored, retransmitted on error, and duplicated for redundancy. None of this is possible for quantum states.
The no-cloning theorem prohibits copying an unknown quantum state. A quantum router cannot read a qubit’s value to make a routing decision and then forward it, because reading collapses the quantum state. A quantum packet cannot be retransmitted on error by reading and resending it. Store-and-forward routing, the backbone of the classical internet, has no direct quantum analogue.
The solution is to use entanglement as the network primitive instead of data packets.
Entanglement as the network primitive
Rather than routing qubits from source to destination, quantum networks distribute entangled pairs between any two nodes on demand. Entanglement can be extended across multiple hops using entanglement swapping at intermediate nodes, without those nodes ever learning the values of the qubits involved. Once two nodes share an entangled pair, they can transmit a qubit between them using quantum teleportation, which consumes the entangled pair and requires a classical side-channel to complete.
This changes the role of the network from a data pipe to an entanglement distributor. The network’s job is to produce shared entangled pairs between endpoints as efficiently as possible; the applications then consume those pairs.
The quantum internet protocol stack
Like classical networking, quantum internet protocols are organized into layers, each building on the one below.
Physical layer. At the bottom, photons travel through optical fiber or free space between adjacent nodes. Protocols at this layer handle photon generation, detection, and the classical signals that announce whether a photon arrived. Key metrics are loss rate, dark count rate (false detections), and timing jitter. Current fiber systems operate at telecom wavelengths near 1550 nm where fiber loss is lowest.
Link layer. The link layer is responsible for generating a single shared entangled pair between two directly connected nodes. This involves attempting to produce entanglement, heralding success via a classical message, and discarding failed attempts. Because photon loss makes each attempt probabilistic, the link layer must handle repeated attempts and track which attempts succeeded. Entanglement purification protocols at this layer can upgrade noisy entangled pairs to higher fidelity at the cost of consuming additional pairs.
Network layer. The network layer extends entanglement from directly connected nodes to arbitrary pairs within the network. It implements entanglement swapping at intermediate repeater nodes, routing decisions about which path to use, and coordination of timing across multiple hops. A key challenge is that entanglement swapping requires the intermediate node to hold quantum memory on both sides simultaneously, so the network layer must orchestrate memory allocation and release.
Transport layer. The transport layer provides end-to-end guarantees: delivering a qubit from source to destination reliably, or establishing a shared entangled pair with sufficient fidelity for the intended application. It handles error recovery, fidelity estimation, and the classical communication needed to complete teleportation.
Application layer. The application layer contains the quantum protocols that users actually run: quantum key distribution, blind quantum computing, distributed quantum sensing, or quantum-enhanced distributed consensus. These protocols consume the entanglement resources provided by the layers below.
Standards and research efforts
The Internet Engineering Task Force (IETF) hosts a Quantum Internet Research Group (QIRG) that is working on architectural frameworks and terminology. As of 2026, this group has published informational documents describing the quantum internet architecture and the properties required at each layer, but formal standards are still early.
Wehner, Elkouss, and Hanson’s 2018 roadmap paper in Science laid out a six-stage progression from simple trusted-relay networks to a fully quantum internet, and it has become a reference framework for discussing where current efforts stand and what comes next.
The Quantum Internet Alliance in Europe coordinates research across academia and industry, working toward a continent-scale quantum network. Several national programs in the US, China, Japan, and the Netherlands are pursuing quantum network testbeds that will serve as proving grounds for protocol development.
Blind quantum computing as a key application
One of the most compelling applications enabled by quantum internet protocols is blind quantum computing. In this protocol, a client with modest quantum capabilities (perhaps only a device that can prepare single qubits) delegates a quantum computation to a powerful remote server without the server ever learning what computation was performed or what the inputs and outputs were.
The server performs operations on qubits provided by the client, but because those qubits arrive in states the server cannot distinguish without knowing the client’s secret parameters, the server’s view is computationally random. Classical computation offers no equivalent: if you send your data to a cloud server to compute on, the server necessarily learns your data.
Blind quantum computing requires quantum communication between client and server, specifically the ability to send individual qubits. As quantum internet protocols mature and links become available, blind quantum computing would allow small organizations to use large-scale quantum computers without trusting the provider with their data.
Relationship to quantum key distribution
Quantum key distribution (QKD) is sometimes described as the first application of a quantum internet, but it occupies an unusual position in the protocol stack. Current deployed QKD systems often operate without a full quantum network underneath: they use point-to-point quantum links and trusted relay nodes, which means the security guarantee holds only end-to-end on each individual link, not across the full path.
A true quantum internet protocol for key distribution would establish entangled pairs directly between Alice and Bob regardless of how many repeater nodes lie between them, enabling information-theoretically secure key distribution without any trusted intermediary. This is the Ekert (E91) protocol, and it requires the entanglement distribution capability that only a full quantum network can provide.
Classical and quantum protocol layers side by side
The analogy to classical networking is useful but has limits:
| Classical | Quantum |
|---|---|
| Physical: electrical/optical signal | Physical: single photons |
| Link: MAC, framing | Link: entanglement generation, heralding |
| Network: IP routing | Network: entanglement swapping, routing |
| Transport: TCP reliability | Transport: end-to-end fidelity, teleportation |
| Application: HTTP, DNS | Application: QKD, blind computing, sensing |
The key difference is that classical layers move data, while quantum layers create shared quantum correlations (entanglement) that applications then consume. Classical routers forward packets; quantum routers broker entanglement. This distinction shapes every design decision in the quantum protocol stack.