Quantum Computing
What is quantum computing?
wikipedia:the use of quantum-mechenical phenomena to perform computation
Some quantum mechanical phenomena
superposition
entanglement
Development
| Early 1980s | Paul Benioff proposed a quantum mechanical model of the Turing machine |
| 1994 | Peter Shor invented Shor's algorithm. |
| 2019 | Google and Nasa claimed to have acheived quantum supremacy. |
quantum supremacy:a quantum computer solves a problem that classical computers cannot.
Aren't classical computers good enough?
?
Quantum computers are fast!
(on solving particular problems)
| classical | quantum | |
|---|---|---|
| factoring integers | exponential time | polynomial time |
| finding data in a dataset | O(N) |
O(\(\sqrt N \))
Shor's alogorithm
Why do we still use RSA?
The largest number factored by Shor's algorithm?
21 = 3 \(\times\) 7
about 1000000000 bits
53 qbits
Pros and Cons
Advantages:
1. Speed up calculation in particular problems
2. Reduces power consumption.
Disadvantages:
1. It makes some encryption not as safe.
2. It is not as stable as classical computers.