Time-optimal quantum computation · HackerPapers discussions

Time-optimal quantum computation — mentioned by Strilanc

Thu, 25 Dec 2025 15:21:49 GMT

Yes, speed matters. No, quantum computers can't do everything instantly even with unbounded qubits. A well studied example is that it's impossible to parallelize the steps in Grover's algorithm. To find a preimage amongst N possibilities, with only black box access, you need Ω(sqrt(N)) sequential steps on the quantum computer [1]. Another well known case is that there's no known way to execute a fault tolerant quantum circuit faster than its reaction depth (other than finding a rewrite that reduces the depth, such as replacing a ripple carry adder with a carry lookahead adder) [2]. There's no…

Paper and discussion history. A mention is not an endorsement.

Time-optimal quantum computation — mentioned by Strilanc

Sat, 04 Sep 2021 23:23:19 GMT

(Disclaimer: I work on google's quantum team and I'm not gonna read the patent for legal reasons.) From the perspective of someone in the field, the title of this article sounds kinda funny. The notable thing would be if the design of some large scale quantum system somehow avoided teleportation. Imagine an article that said "AMD proposes transistors to make computing more efficient" and you'll get a sense of what I mean. Teleportation is one of the first things you will learn about in an introductory quantum computing course. It is an incredibly useful building block, with even more useful…

Paper and discussion history. A mention is not an endorsement.