Preskill traces the idea to Richard Feynman, who argued that quantum systems could simulate other quantum systems that ordinary computers struggle to model. Peter Shor’s factoring algorithm later showed that quantum computers might also help with problems beyond physics, including ones relevant to cryptography.
Quantum Computing
Speaker
John Preskill, a Caltech physicist, explains quantum computing and its prospects in a Y Combinator conversation with a host.
Preskill compares entangled qubits to pages in a book whose information is stored in correlations between pages, not in any page by itself. Quantum error correction uses those correlations to protect information from environmental noise, which can disturb a quantum state when information leaks out.
Preskill says it is difficult to predict the uses of a new kind of information processing, but expects quantum computers to help model molecules and materials. He describes Grover’s algorithm as a way to speed up exhaustive search, while stressing that its practical gain is limited compared with the exponential speedup proposed for factoring.
Preskill describes competing hardware approaches, including trapped ions, superconducting circuits, electron spins, and topological qubits. He says both qubit count and gate reliability matter, and discusses the threat to RSA and elliptic curve cryptography alongside post-quantum cryptography and quantum key distribution.
Preskill connects his interest in quantum information to questions about gravity and the structure of space-time. He suggests that entanglement may underlie geometry and that future quantum devices could let researchers study highly entangled systems that digital computers cannot readily simulate.
Takeaways
- Assess quantum hardware by gate reliability and control as well as qubit count.
- Treat quantum error correction as a way to protect information encoded across correlations.
- Explore near-term quantum applications through experiments, while accounting for noise and limited scale.
- Plan for cryptographic migration: Preskill says quantum computers could eventually threaten widely used public-key systems.
- Build teams that can communicate across hardware, control, software, and applications.
Mentioned in this talk
Microsoft
IBM
Intel
GoogleThe Theoretical MinimumQuantum information science and technologyquantum error correctionQuantum entanglementGrover's algorithmquantum interferencetrapped ionssuperconducting circuitstopological quantum computingpublic-key cryptographypost-quantum cryptographyquantum key distributionquantum repeatersquantum sensingRichard FeynmanPeter ShorLeonard SusskindSearch inside this talk
What was claimed 10
- featureRichard Feynman: Proposed using a quantum system to simulate another quantum system; called it a universal quantum simulator.
“To simulate nature, it should be quantum mechanical.”
YouTube Unverified1 source· Talk
- featurequantum error correction: Encodes quantum information so it remains robust despite uncontrolled interactions with the environment.
“we developed a theory called quantum error correction.”
YouTube Unverified1 source· Talk
- featureGrover's algorithm: Speeds up exhaustive search, allowing about twice as many possibilities to be handled at the same processing speed.
“What Grover's algorithm does is speed up that exhaustive search.”
YouTube Unverified1 source· Talk
- uses
“That's actually what Microsoft is pushing very hard.”
YouTube Unverified1 source· Talk
- metricsuperconducting circuits: Coherence times increased by about a factor of 10 every three years over roughly 15 years.
“those coherence times have increased by about a factor of 10 every three years”
YouTube Unverified1 source· Talk
- featureIntel: Works on quantum technology, including hardware, fabrication, control, software, applications, and user interface.
“Some of the companies working on quantum technology now include well-known big players like IBM, Google, Microsoft, and Intel.”
YouTube Unverified1 source· Talk
- featureGoogle: Works on quantum technology, including hardware, fabrication, control, software, applications, and user interface.
“Some of the companies working on quantum technology now include well-known big players like IBM, Google, Microsoft, and Intel.”
YouTube Unverified1 source· Talk
- featureIBM: Works on quantum technology, including hardware, fabrication, control, software, applications, and user interface.
“Some of the companies working on quantum technology now include well-known big players like IBM.”
YouTube Unverified1 source· Talk
