Qubits & Quantum Mechanics - Explained
October 23, 2019
Google achieved Quantum Supremacy
54-Qubit Sycamore processor
Verify whether a set of numbers is randomly distributed or not
IBM Summit
10,000 years
3 minutes & 20 seconds
Quantum computer is a computer that runs on Qubits instead of traditional Bits
Modern computers store the information in units of digital bits 0 or 1.
What are these 0s & 1s?
It is on the hardware level -> whether the current is flowing through a transistor or not
Transistors are semiconductor devices that can be controlled to allow or block flow of current
If current is allowed it's "on" state or 1
If current is blocked it's "off" state or 0
This flow of current is basically flow of "electrons" through the electrical circuit
Flow of electrons are blocked in the "off" state by introducing a barrier of insulating materials

In "on" state - no barriers

In "off" state - a barrier cuts off the flow of electrons

Size of modern transistors

The smallest working transistor ever created is 1nm

Transistor count ∝ Performance
Apple's mobile phones have 7nm chips (A13 Bionic)

Red Blood Cells - 10,000 nm

Bacteriophage virus - 15 nm

Modern Transistors - 7 nm

Smaller the size of the transistor

Smaller the size of the barrier blocking the electron

If the barrier get's too small... something wierd happens
The electron "teleports" through the barrier due to a property called Quantum Tunneling

Which only happens in the "Quantum realm"

Property 1: Quantum Tunneling
It is property of particles where they don't move but instead teleport through different places
What we observe in the normal realm is basically the positions they occupy with the highest probability of getting teleported to
Another problem with using Bits -> exponential problems
The performances of a bit increases linearly

4 Bits -> can have only 1 of all possible 2^4 values

Problem solving is basically going through all the 2^4 values and finding that one required value

Problems whose complexity grows exponentially
Chess & Rice Grains
64th Square - 18,000,000,000,000,000,000 grains of rice
Spin of an Electron
Polarization of a Photon
Property 2: Quantum Super Position
Might sound stupid
Photon may be polarized both vertically & Horizontally when it is not observed
Which means at any given time a qubit is both 0 & 1!
While bit is 0 or 1
4 Bits -> can have all the possible 2^4 values
When we observe it -> it'll collapse to 1 value

To solve the problem we just have to collapse all the unnecessary values & find the 1 required value
Database Search
Regular Computers - O(n)
Quantum Computers - O(√n)
Searching a DB with 10,000,000 entries
Time complexity of 3162
Areas influenced by the Quantum Computers

Prime Factorization of large number (1024 bit)


Quantum Computers can simulate theoretical chemistry much more efficiently

Biological Simulations

Simulate how a drug interacts with the human body greatly increasing the efficiency of drug production

Pandemic Response

Predict how a pandemic will spread by crunching the numbers & provide effective response strategy

Property 3: Quantum Entanglement
The property of quantum computers in which a qubit gets entangled to another qubit
Any interaction on one Qubit will be "immediately" reflected in the another one

0ms response time

No matter how far they are!

Get Started!
IBM Quantum Experience
Azure Quantum
AWS Braket

Thank You!

daniakash.com | @dani_akash_