# How many physical qubits are needed to encode a logical qubit on ion trap, superconducting, neutral atom, photonic QC?

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?

• 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?” Nov 19, 2021 at 3:54
• 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. Nov 19, 2021 at 20:00
• 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?" Nov 22, 2021 at 18:11
• @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 ? Nov 24, 2021 at 17:57