But, what is this good for?Clive Cenxin Aw, Zaw Lin Htoo3 November 2023, Friday Hacks 745pmQuantum Theoryrd
My talk
1. The How of Quantum
(oh no, maths)
2. The So What of Quantum
(can eat or not)
label this “0”label this “0”
label this “1”label this “1”
What’s weird is that discrete objects can be in superposition and interfere
discrete
mutually exclusive outcomes
We only ever find a photon “here” or “there” with certain probabilities
input
output
Born Rule: Probability of obtaining is the square of the number in front of
Generally, beamsplitters can reflect and transmit different amounts of light
This is like having quantum bits with the Born rule that determines the output
qubits
Beamsplitters = Single-qubit Transformations
can be ignored becausewe’ll be squaring it
Single-bit Transformations = Single-bit Logic Gates
The action of the beamsplitter reminds us of classical logic gates
Single-qubit Logic Gates
Indeed, there are direct quantum analogues of one-bit logic gates
But the beamsplitter itself has no classical counterpart
And general beamsplitters, even less so!
The closer it is to , the more likelyyou would observe 0
Outcome probabilitiesaccording to Born’s rule
These gates compose as we expect
Summary of Some Single-qubit Gates
A Two-qubit Gate
We also have two-qubit controlled-logic gates