# How the various quantum gates are implemented physically in quantum computer?

I'm not able to find any sources. Can you point me to some?

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Mani Bharathy is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
• Welcome on the QC SE! I think yes, there are a lot of sources, although most of them is hard. If the community finds your question too broad ("needs more focus"), I suggest to read some of them, and then ask the details of a specific implementation (like by photon spins or so). What you learn in this process, will help you to ask this time much more liked (=upvoted) questions. – peterh - Reinstate Monica Jan 13 at 20:51
• Quantum computation and quantum information from Nielsen and Chuang + Quantum computing for computer scientist from Yanofsky and Noson – BrockenDuck Jan 13 at 21:23
• Does this answer your question? What is the physical representation of a qubit? – Mark S Jan 14 at 4:50

I found this interesting article that talks about creating a Fredkin quantum gate (controlled SWAP) : https://advances.sciencemag.org/content/2/3/e1501531

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SebastienFrom128mots.com is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.

This playlist by QuTech Academy on the 'building blocks' of a quantum computer might offer some nice insights.

• Video $$10$$ & $$11$$ introduce spin qubits, with the second video specifically on the operations on spin qubits.

• Video $$12$$ & $$13$$ introduce NV centre qubits, with again the second video specifically on the operations on spin qubits.

• Video $$14$$ through $$19$$ introduce the widely used transmon qubits, with measurements, single-qubit operations and the two-qubit operation in separate videos.

• Video $$20$$ through $$25$$ introduce the concepts behind a majorana-based topological quantum computer, but so far there's little 'physical' about that (unfortunately)

Notable omissions include (as QuTech doesn't work on these technologies):

• Trapped ion systems. Check for instance this video by MIT Opencourseware for the basics.
• Photon-based systems, most notably the linear KLM model. Check the (wiki)link for the introduction on how the gates are implemented (hint: beam splitters and mirrors).

Of course there's also adiabatic-style quantum computers, but there you don't perform 'gates', you just tune the coupling between qubit neighbour pairs.

Realization of efficient quantum gates with a superconducting qubit-qutrit circuit

Although the proposed setup is rather experimental, it may give you some ideas how to implement gates on computers with superconducting qubits.