Quantum computers towards a reality

(MainsGS3:Awareness in the fields of IT, Space, Computers, robotics, Nano-technology, bio-technology and issues relating to intellectual property rights.)

Context:

• The 2022 Nobel Prize for physics was awarded  “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science” which shows the importance of quantum computing.

Computers use classical physics:

• Quantum computers (QC) is their ability to take advantage of quantum physics to solve problems too complex for computers that use classical physics.
• Several institutes, companies and governments have invested in developing quantum-computing systems, from software to solve various problems to the electromagnetic and materials science that goes into expanding their hardware capabilities.
• In 2021 alone, the Indian government launched a National Mission to study quantum technologies with an allocation of ₹8,000 crore; the army opened a quantum research facility in Madhya Pradesh; and the Department of Science and Technology co-launched another facility in Pune.
• Given the wide range of applications, understanding what QCs really are is crucial to sidestep the misinformation surrounding it and develop expectations that are closer to reality.

At the subatomic scale:

• The classical ‘experience’ of reality tells that a macroscopic object can be at only one location at a time; this location can be predicted accurately; and the object’s effects on its surroundings can’t be transmitted faster than at the speed of light. 
• Quantum physics describes reality at the subatomic scale, where the objects are particles like electrons and in this realm, one can’t pinpoint the location of an electron.
• One can only know that it will be present in a given volume of space, with a probability attached to each point in the volume – like 10% at point A and 5% at point B.
• When you probe this volume in a stronger way, you might find the electron at point B and if you repeatedly probe this volume, you will find the electron at point B 5% of the time.

Use of superposition:

• The bit is the fundamental unit of a classical computer. Its value is 1 if a corresponding transistor is on and 0 if the transistor is off.
• The transistor can be in one of two states at a time – on or off – so a bit can have one of two values at a time, 0 or 1.
• The qubit is the fundamental unit of a QC which is typically a particle like an electron.
• Some information is directly encoded on the qubit: if the spin of an electron is pointing up, it means 1; when the spin is pointing down, it means 0.
• But instead of being either 1 or 0, the information is encoded in a superposition: say, 45% 0 plus 55% 1 which is entirely unlike the two separate states of 0 and 1 and is a third kind of state.
• Further, the qubits are entangled to ensure they work together thus, if one qubit is probed to reveal its state, so will some of or all the other qubits, depending on the calculation being performed. The computer’s final output is the state to which all the qubits have collapsed.

Conclusion:

• A quantum computer can solve problems rapidly because it can attack complex problems that are beyond the scope of a classical computer with the basic advantage of speed as it is able to simulate several classical computers working in parallel.