Quantum computing


    In News

    • The 2022 Nobel Prize for physics was awarded for work that rigorously tested and paved the way for its applications in computing which shows the importance of Quantum computing in contemporary times.

    What is Quantum Computing?

    • Meaning:
      • Quantum computers mimic the behaviour of atoms and subatomic particles to drastically increase processing speed
      • These particles can exist in several states simultaneously, a puzzling phenomenon called quantum superposition.
    • Important Terms:
      • Superfluid: quantum processors need to be very cold – about a hundredth of a degree above absolute zero. To achieve this, we use super-cooled superfluid to create superconductors.
      • Superposition: Groups of qubits in superposition can create complex, multidimensional computational spaces. Complex problems can be represented in new ways in these spaces.
      • Entanglement is a quantum mechanical effect that correlates the behaviour of two separate things. When two qubits are entangled, changes to one qubit directly impact the other. Quantum algorithms leverage those relationships to find solutions to complex problems.
    • There are many interpretations of the laws of quantum physics:
      • Copenhagen interpretation: Erwin Schrödinger popularised it using a thought-experiment he devised in 1935.
        • It stated that when you probe the volume, you force the superposition of the electrons’ states to collapse to one depending on the probability of each state.
      • Entanglement: When two particles are entangled and then separated by an arbitrary distance (even more than 1,000 km), seeing one particle, and thus causing its superposition to collapse, will instantaneously cause the superposition of the other particle to collapse as well. 
        • This phenomenon seems to violate the notion that the speed of light is the universe’s ultimate speed limit.


    • Quantum computing uses phenomena in quantum physics to create new ways of computing.
    • Quantum computing involves qubits. 
    • Unlike a normal computer bit, which can be either 0 or 1, a qubit can exist in a multidimensional state.
    • The power of quantum computers grows exponentially with more qubits.
    • Classical computers that add more bits can increase power only linearly.

    How would a computer use 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. 
      • It’s typically a particle like an electron. 
      • Google and IBM have been known to use transmons, where pairs of bound electrons oscillate between two superconductors to designate the two states.
      • 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. This is entirely unlike the two separate states of 0 and 1 and is a third kind of state.
    • One qubit can encode two states. Five qubits can encode 32 states. A computer with N qubits can encode 2N states – whereas a computer with N transistors can only encode 2 × N states.
      • So a qubit-based computer can access more states than a transistor-based computer, and thus access more computational pathways and solutions to more complex problems. 

    Quantum Computer vs. Classical Computer

    Commercial Applications

    • Financial Services: There is a potential for quantum computers to shed insights into larger problems where constraints are relaxed and where more outcomes are possible.
    • Cybersecurity: The World Economic Forum has highlighted that “quantum computing could make today’s cybersecurity obsolete.” This is because the technology underlying modern cryptography uses combinatorics.
    • Chemical engineering: Developing new useful molecules requires combinatorics because there are many possible combinations of atoms, and many possible ways that they can bond.
    • Advanced manufacturing: Artificial Intelligence helps in making manufacturing more efficient by identifying the cause of rare failures in their manufacturing processes.
      • These are difficult combinatorics problems, related to finding a single fault in systems where many possible sequences need to be investigated.
    • Machine learning: Improved ML through faster structured prediction. Examples include Boltzmann machines, quantum Boltzmann machines, semi-supervised learning, unsupervised learning and deep learning.
    • Healthcare: DNA gene sequencing, such as radiotherapy treatment optimization/brain tumour detection, could be performed in seconds instead of hours or weeks.


    • Expensive refrigerators: Because of their sensitivity to environmental disturbances, quantum computers today are highly unstable and must be held in expensive refrigerators cooled to near-absolute zero temperatures.
    • Threat to National Security: Quantum AI tools, for instance, can provide autonomous weapons and mobile platforms, such as drones, with heightened sensing, navigation, and positioning options in GPS-denied areas. Equipped with quantum AI tools, such systems could also independently alter course to avoid enemy countermeasures.
    • Cyberattacks: Quantum also has the potential to significantly increase the connectivity, security, and speed of the internet. This architecture, which uses quantum cryptography, could usher in a super-secure communications infrastructure that shields internet-connected devices, including critical infrastructure, from cyberattacks.
    • Error correction during the computing stage hasn’t been perfected: That makes computations potentially unreliable. Since qubits aren’t digital bits of data, they can’t benefit from conventional error correction solutions used by classical computers.
    • Retrieving computational results can corrupt the data: Developments such as a particular database search algorithm that ensures that the act of measurement will cause the quantum state to decohere into the correct answer hold promise.

    Government Initiatives

    • National Mission to study quantum technologies: the Indian government launched a National Mission to study quantum technologies with an allocation of ?8,000 crore. 
    • Quantum research facility: the army opened a quantum research facility in Madhya Pradesh and the Department of Science and Technology co-launched another facility in Pune.
    • QuEST: The Department of Science and Technology launched the Quantum-Enabled Science and Technology (QuEST) initiative to invest INR 80 crores to lay out infrastructure and to facilitate research in the field.
    • Quantum Computer Simulator (QSim) Toolkit: It provides the first quantum development environment to academicians, industry professionals, students, and the scientific community in India.

    Way forward

    • Increasing Investments: 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.
    • While quantum computing has the enormous potential to revolutionize how real-world issues are tackled, there are still numerous difficult engineering challenges to overcome first, leaving companies without a timeframe for when it will be used in the workplace.

    Source: TH