Breakthrough Prize in Fundamental Physics 2023

เสวนาสาธารณะ 6 ตุลาคม 2565

Photo credit: Breakthrough Prize

Dancing with Qubits

How they can change the world

Qubit

Probabilistic prediction

Choice of measurement +

Quantum state =

Certainty

Fully random

Somewhat random

Qubit

Even ideal measurements cause "collapse of the wave function" 

or

or

or

But in quantum theory, different choices of measurement can be incompatible

Not too different from updating your belief

Entanglement

These different choices of measurement can reveal stronger-than-classical correlation when the qubits are entangled

If not for these measurement choices, entanglement would be no different from a classical correlation

\(\to\) See Nobel Prize in Physics 2022

BB84 Quantum Key Distribution

Modified from Zbinden et al. Appl. Phys. B (1998)

Stephen Wiesner (1942-2021) proposed using qubits to create money that would be impossible to counterfeit by the no-cloning theorem, while the authenticity of the money could be verified by measuring the qubits in the correct basis. 

Wiesner's Quantum Money

Bennett and Brassard, QCrypt 2015

(This is before the "official" discovery of no-cloning theorem and super-dense coding!)

Early Timeline of Quantum Computing

1981

Quantum computing for simulation of physics

1985

Quantum Turing machine, Deutsch-Josza algorithm (1992)

1994

Shor's factoring algorithm, quantum error correcting codes (1995)

1994

Implementation proposal using trapped ions