Could you elaborate which aspect of bitcoin has efficient quantum algorithms?
BitCoin uses public key cryptography for its digital signatures. That in turn relies on the difficulty of factoring large numbers, for which there are efficient quantum algorithms.
Bitcoin actually uses ECDSA for its digital signatures, which relies on the difficulty of calculating discrete logarithms rather than factoring. However I believe that there are efficient quantum algorithms for that, too.
BitCoin uses public key cryptography for its digital signatures. That in turn relies on the difficulty of factoring large numbers, for which there are efficient quantum algorithms.