Quantum Computer- Gateway to Revolution
Now, is the era for the biggest upgrade of our brains….
Since the 1960s, the power of our brain machines has kept growing exponentially, allowing computers to get smaller and more powerful at the same time,
But, this process is about to meet its physical limits.
Inside every modern computer, we have ICs(Integrated Circuits) which further consist of modules and which is further made up of logic gates, which is further made up of transistors(mostly MOSFET).
The size of a transistor which is used inside our traditional computer system is only 14 nanometers, which is 8 times smaller than an HIV virus, and 500 times smaller than a red blood cell.
(Even the engineers at MIT had developed a robot barely the size of a cell.)
It has reached its physical barrier because transistors are approaching barely the size of an atom, the transistor act as a switch for the electrons which are passing through it.
It can either allow or restrict the flow of electrons. It acts as a physical barrier to the electrons which is the basis of binary computing. If we further decrease the size of a transistor, then electrons can transfer to another side of the blocked passage. This phenomenon is known as quantum tunneling.
In quantum physics, things work differently from the predicted ways we are used to. So, scientists are trying to use the unusual quantum properties to their advantage, by building quantum computers.
Binary computers
Any technological device that we use today works on the basis of binary computing.
Binary computers use the sequence of 0s and 1s to derive meaning from our inputs and produce outputs.
It’s more like a group of 7 years old who are calculating very simple maths problems and a very large group of them can simply calculate anything from Astrophysics to Zelda.
7 bit: 128(2⁷) different ASCII characters
32 bit: 4 billion (2³²) ram addresses
Take for example a computer program.
Objective- To check whether a number is prime or not.
Consider a simple program in C language.
#include<stdio.h>
int main()
{
int n, c = 2;
printf("Enter the number of prime numbers required\n");
scanf("%d",&n);
for ( c = 2 ; c <= n - 1 ; c++ )
{
if ( n%c == 0 )
{
printf("%d isn't prime.\n", n);
break;
}
}
if ( c == n )
printf("%d is prime.\n", n);
return 0;
}In this program, the value of ‘c’ is incremented from ‘2’ by “1” till its value becomes “n-1”. On every incrementation, “c” is divided by “n” to check if a remainder is obtained.
Although it is an easy program, the process of incrementing the value of ‘c’ by ‘1’ and checking the condition in every iteration will take a lot of time.
To decrease the time complexity of the solution, we can change the values of ‘c’ from 2 to √n, but it’s still insufficient if we want faster results. What if we could use all the values of ‘c’ at the same time to check whether ’n’ leaves a remainder when divided by ‘c’?
Quantum computing could help us do this using qubits to solve problems.
Qubits
Qubits, aside from sounding way cooler, have extra functions that bits don’t. A qubit can be any two-level quantum system, such as a spin or a magnetic field or a single photon. ‘0’ and ‘1’ are their two possible states like a photon’s horizontal or vertical polarization. In the quantum world, the qubit doesn’t have to be any one of those. It can be of any proportions of both states at once. This phenomenon is called superposition. But when you have to observe its state, it has to decide any one of the values. So, as long as it’s unobserved, the qubit is in a superposition of probabilities for ‘0' and ‘1’, and you can’t predict which it will be. The instant you measure it, it collapses into one of the definite states. Superposition is a game changer.
So, qubits allow us to choose multiple possible combinations at a time.
Coming back to the problem, if we even have all the possible combinations of 0s and 1s at the same time, still we will have to check it with the test expression.
Quantum computer can use superposition and entanglement at the same time. This can be exponentially more efficient than would ever be on a normal computer.
Entanglement
A close connection that makes each of the qubits react to change in each other’s state instantaneously, no matter how far they are apart means that when measuring just one entangled qubit, you can directly deduce properties of its partners, without having to look.
A normal logic gate gets a simple set of inputs and produces one definite set of output.
A quantum gate manipulates an input of superposition, rotates probabilities, and produces another superposition as its output.
So, a quantum computer sets up some qubits, applies quantum gates to entangle them and manipulate probabilities, then finally measures the outcome, collapsing superposition to an actual sequence of 0’s and 1’s.
This makes quantum computers very fast when it comes to searching for any file in a database.
Quantum entanglement is actually teleportation.
Last year, a group of Chinese scientists used quantum teleportation to send a message from a satellite in space to two separate ground stations on Earth.
The team created pairs of photons that were separated by distance, but not time. These photons mirror one another, so a message inserted into one of them is instantly reflected in the other. This allowed the scientists to communicate using the light without being limited by the speed of light.
Quantum supremacy and economy
Quantum Supremacy can economically strengthen a country because various industries in the world want to explore the fields of quantum computing to use it for their benefit factor. But, till now we have been able to build only a 50 qubits quantum computer.
Why can’t we just add more qubits to the system?
Understanding what the problem exactly is
Manipulation of the subatomic particles in an atom cannot be done at higher temperatures, they need temperature near to 0 Kelvin which cannot be achieved easily. So, the qubits are kept in highly sophisticated refrigerators and are very sensitive to external factors.
There is another problem called quantum decoherence.
Quantum decoherence happens when losing information to the environment over time. The “timer” doesn’t start until we try to do something with qubits, like measure them or perform a computation. It induces noise in our output which makes it unreadable.
(Google made a 72 qubit quantum computer but it’s of hardly any use due to a large amount of noise.)
Quantum computer is believed to be a threat to national security
The moment you will google the term “quantum computer” you are definitely going to come across articles explaining quantum computers as a threat to national security and how shor’s algorithm can break our present RSA encryption.
It is theoretically proven that Shor’s algorithm (which is made for theoretical quantum computers) can break our present RSA algorithm, which is used for encryption and uses 128–256 bit system. In the RSA algorithm, we have a gargantuan number which is the multiplication of two prime numbers. There are 2 keys used in this system- the “public key” and the “private key”. You can share the public key with anyone (it can only be used to access the product of two prime numbers) and the private key stores the correct set of two prime numbers to decrypt the message.
Shor’s algorithm gives us a way to get those 2 prime number using the public key within a very short period of time.
But, the fact is that today, the quantum computer we have only has 50 qubits. But for running Shor’s algorithm for Garganta number we need millions and millions of qubits.
So, we are still very far away from our security being threatened by quantum computers. It’s not a thing of national security at least right now.
States on Quantum Computing
Their has been a competition among states to achieve technological superiority…
For example,
The U.S. Congress is cautious enough to take the first step to accelerate the development of quantum technology. Pending legislation such as the National Quantum Initiative Act sets up an important 10-year pilot program to advance research of quantum applications for economic and national security implementations.
Even the Chinese are not lagging behind…
The Chinese scientists are developing a way to encrypt telecommunication networks for national security purposes, using quantum computers known as the “quantum internet” which will be unhackable. (In collaboration with Chinese E-commerce Giant Alibaba)
At last…
We should end up the race to compete against each other…
Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world.
In the future, however, quantum computers will change our entire understanding of biology, chemistry, and physics. Simulations at the molecular level could be conducted that actually imitate physical concepts in the universe we’ve never been able to reproduce or study.
