If two QPUs can share entanglement, can any pair of qubits be entangled?

Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Stack Overflow for Teams is now called Stack Internal. Bring the best of human thought and AI automation together at your work. Bring the best of human thought and AI automation together at your work. Learn more TeamsQ&A for workConnect and share knowledge within a single location that is structured and easy to search.Considering that QPUs A and B have a physical link between them, does it mean that any pair of qubits can be entangled? Or only specific qubits will have the possibility of being entangled?It depends on what you mean and the qubit modality you are exploring. For example, ion trap quantum computers, like those from Quantinuum, boast all to all connectivity, meaning that any one qubit can entangle with another directly. In superconducting quantum computers, this is often not the case, so the limitation between entangling one random qubit on one QPU with a random qubit on a second QPU would be the coherence time of both qubits and the speed with which entanglement (broadly, CNOT) gates can be applied. Thus, the underlying hardware process to entangle qubits across QPUs varies vastly in terms of the execution needed (and engineering that needs to be done), but in an ideal, post-NISQ quantum computer, the addition of a second quantum "chip" would allow for entanglement, one of the critical parts of quantum computing, to exist robustly.An interesting arXiv article on the topic can be found hereThanks for contributing an answer to Quantum Computing Stack Exchange!But avoid …Use MathJax to format equations. MathJax reference.To learn more, see our tips on writing great answers.Required, but never shown By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy. Start asking to get answersFind the answer to your question by asking.Explore related questionsSee similar questions with these tags.To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Site design / logo © 2025 Stack Exchange Inc; user contributions licensed under CC BY-SA . rev 2025.11.20.37056