How many physical qubits are needed to encode a logical qubit on an

-- ion trap,

-- superconducting,

-- neutral atom,

-- photonic,

-- spin

quantum computer based on today's technologies?

  • 1
    $\begingroup$ This is pretty broad right now. Maybe consider asking “what factors determine the number of physical qubits needed to encode a logical qubit, as applied to current (2021) devices?” $\endgroup$ Nov 19, 2021 at 3:54
  • $\begingroup$ What do you mean by "encode a logical bit"? Qubits are a superset of regular 0/1 bits. I can just use the collapsed state of a Qubit as a classical bit...but that wouldn't be very wise since I could just use a regular bit for that. $\endgroup$ Nov 19, 2021 at 20:00
  • $\begingroup$ The answer depends on quantum error correction codes, which you use. Any ECC performs exactly the same regardless of the physical medium. The only difference is: "is this QC scheme has enough gate fidelity for this ECC to be effective?" $\endgroup$
    – totikom
    Nov 22, 2021 at 18:11
  • $\begingroup$ @totikom, thank you for the comments. So the original question is, given the fidelity of different QC hardware, how many physical qubits will be required to encode a logical qubit ? $\endgroup$
    – david
    Nov 24, 2021 at 17:57


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