A New Lower Bound Technique for Quantum Circuits without Ancillae
نویسنده
چکیده
We present a technique to derive depth lower bounds for quantum circuits. The technique is based on the observation that in circuits without ancillæ, only a few input states can set all the control qubits of a To↵oli gate to 1. This can be used to selectively remove large To↵oli gates from a quantum circuit while keeping the cumulative error low. We use the technique to give another proof that parity cannot be computed by constant depth quantum circuits without ancillæ.
منابع مشابه
A New Lower Bound Technique for Quantum Circuits without Ancillæ
We present a technique to derive depth lower bounds for quantum circuits. The technique is based on the observation that in circuits without ancillæ, only a few input states can set all the control qubits of a Toffoli gate to 1. This can be used to selectively remove large Toffoli gates from a quantum circuit while keeping the cumulative error low. We use the technique to give another proof tha...
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