24 Sep

Quantum Computers

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Content

• Basics
• Quantum Supremacy
• National Quantum Computing Mission, 2023
• Quantum entanglement
• Quantum cryptography

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Basics

Classical computers have enabled the information revolution that we are part of today. But these classical computers can’t do a number of things including Optimization, Simulation of large molecules, factoring of large numbers etc.

But Quantum computing may help us solve the above problems someday.

Quantum computers are based on the principle of quantum theory and gains enormous processing power by the ability of quantum bits to be in multiple states and due to the ability of quantum computer to perform task using all possible permutations simultaneously.

Quantum Computers use qubit (Quantum bit). These qubits can take values 0 or 1 or any of the infinite superpositions between 0 and 1. When Qubits are in superposition, it has some probability of being in state 0 and some probability of being in state 1.

Quantum computing also borrows inspiration from another property of quantum mechanics called entanglement, wherein the two qubits could be connected in such a way that the state of one qubit intrinsically affects the state of the other qubit.

Each operation of a quantum computation is performed by a quantum gate, which like classical gate, changes the state the qubits are in.

A) Quantum Supremacy

It refers to quantum computers being able to solve a problem that a classical computer cannot. The term was coined by theoretical physicist John Preskill of the California Institute of Technology in 2012.

• Google recently used a 53 Qubit processor to generate a sequence of millions of numbers, that conform to an algorithm generated by google. A classical supercomputer checked some of these values and they were correct.
• Google’s Quantum computer claimed ‘Supremacy’ because it reportedly did the task in 200 seconds that would have apparently taken a supercomputer 10,000 years to complete.

Some Problems faced by Quantum Computing Sector: While the above concept sounds promising, but there are still tremendous obstacles to be overcome.

• Interference: During the computation phase of a quantum calculation, the slightest disturbance in the quantum system (a stray photon or a wave of EM radiation) causes the quantum computation to collapse, a process known as Quantum Decoherence.
• Error Corrections: Because truly isolating the quantum system has proven so difficult, error correction systems for quantum computing have been developed.
• Output observance: Observing the final output also risks corrupting the data.

The breakthroughs in the last 20 year including the quantum supremacy achieved by Google have increased the chances of developing practical quantum computing mechanisms. However, it is not clear whether the practical application is less than a decade away or a hundred years into the future.

Example of Quantum Computers developed so far: While the idea governing quantum computers have been around since the 1990s, the actual machines have been around since 2011, most notably built by Canadian company D-Wave systems. The recent Google’s 53 qubit supercomputer is called Sycamore.

Applications: The potential that this technology offers are attracting tremendous interest from both the governments and the private sector. The quantum computers have the potential to easily tackle computational problems that may be tough for the classical computer. The basic advantage is speed as it can stimulate several classical computers working in parallel.

Military Applications include breaking of advanced encryption using brute force searches.

Advanced Cryptography: Quantum uncertainties could be used to create private keys for encrypting messages to be sent from one place to another. This is the best antidote against quantum computers and employs quantum phenomenon to ensure complete protection of information.

Faster Data analysis in industrial science applications will enable faster solution to business problems in the era of big data.

• Improved Optimization for complex problems like NP-hard problems. This may lead to faster optimization of very large scale problems involving complex network structures, computational biological science, and physical sciences.
• Transform Healthcare and Medicine: For instance, the design and analysis of molecules for drug development is a challenging problem today.

Other civilian applications include DNA Modelling and complex material science analysis.

• Improved Machine Learning Outcomes by enabling more efficient optimization of these algorithms so that ML capabilities become more efficient, accurate and fast.
• Teleporting the information from one location to another without physically transmitting the information. Entangling of quantum particles allow us to achieve this.

India and Quantum Computing:

There are no quantum computers in India yet.

Cabinet Approves Rs 6003 Crore National Quantum Mission (April 2023)

In Budget 2020-21, government has announced National Mission on Quantum Technologies and Applications which will be allocated Rs 8,000 crore over the next 5 years.

• Although the amount is low to begin with but given the advances in technology and India’s ability to create low-cost solutions, the money may suffice.

In Aug 2021, India launched QSim to aid Quantum Computing research in India.

Way Forward:

• Well-funded Research Centres of Excellence – in the leading technological institutions. A long-term program by DST could possibly be introduced whereby strategic infrastructure and manpower training projects can be funded in the established technology engineering This would need to cover both hardware and software to further develop a homegrown technology industry.
• Clear and Sustained Policy and Governance: Since quantum computers will deal with new levels of data and computing, it’s important to create legal framework surrounding data management, data sharing, data privacy, information assurance, algorithmic governance, and transparency needs to evolve.
• Manpower Skilling is an important component of employability of the future workforce of India, and this may require policy interventions since most private organizations focus on exploiting immediate skill availability and project needs by compromising future skilling needs.
• International Collaboration: International funding agencies could develop joint project funding schemes whereby collaborations can be fostered to enable faster development in the space.
• Encouraging Startups focus on quantum computers: Through, government support via organizations like technology development boards, where grants can be given to startup ventures.

Conclusion: Quantum computing domain needs greater focus in the country through strategic investment in research, development, and training mechanisms. This may enable improved capability for leveraging and exploiting this domain for the benefit of citizens and the nation going forward.

A)National Quantum Computing Mission, 2023

NQM, planned during 2023-2031, will mainly work towards strengthening India’s research and development in the quantum arena alongside indigenously building quantum-based (physical qubits)

It will also entail development of satellite based secure communications between a ground station and a receiver located with 3,000 kms during the first three years.

• For satellite-based communication between Indian cities, NQM will lay communication lines using Quantum Key Distribution over 2,000 kms.

For long distance communication, tests will be conducted in coming years.

Under NQM, there would be four broad themes:

• Quantum Computing
• Quantum Communication
• Quantum Sensing and Meteorology
• Quantum Material and Devices

Thematic hub for each will be established at research institutes and R&D centres who are already working in the field of research.

Department of S&T (DST) will lead the mission, supported by other departments.

The mission put India among the top six leading nations involved in the R&D in quantum technologies. Presently, R&D work in quantum tech is underway in USA, China, Canada, France, Finland and Australia.

B) Quantum Entanglement

Details

What is quantum entanglement?

• Two particles, having ‘interacted’ with each other at some stage, were found to have got ‘entangled’ in a way that the behaviour of one produced an instantaneous reaction in the other even if the two were no longer connected in any way and were separated by large distances.

Contribution of the three scientists: These three scientists over the last four decades, have conclusively established that the ‘entanglement’ phenomenon observed in quantum particles was real, not a result of any ‘hidden’ or unknown forces, and that it could be utilized to make transformative technological advances in computing, hack-free communication, and science fiction like concept of ‘teleportation’.

Details of their contribution:

• The first half of the 20^th century, saw the development of Quantum Physics which explained the seemingly bizarre behaviour of sub-atomic particles with remarkable accuracy.
• Quantum theory explained many phenomenon of quantum particles such as Superposition and Entanglement which were completely against everyday experience.
• Albert Einstein, in particular was very uncomfortable with this. His Special theory of relativity prohibited any signal from travelling faster than the speed of light. The seemingly instantaneous communication due to entanglement went against Einstein’s theory. Therefore, Einstein proposed that something was missing and the Quantum theory was incomplete.
• However, experimentalists were discovering that almost every prediction made by quantum theory were being obeyed by sub-atomic particles. Till, that time, experiment to test entanglement didn’t appear feasible.
• In 1964, John Bell showed how phenomenon of entanglement could be established by experimentalists.

– The famous Bell’s inequality, if maintained in the results of the experiment, would mean that Einstein was right. If violated, it would provide the predictions of quantum theory.

• John Clauser was the first person to set up an experiment to test entanglement. In 1972, his experiments produced results that were clear violations of Bell inequality
• Alain Aspect is credited with vastly improving the set-up of Clauser and removing all the loopholes critics had found. His experiments also produced results that violated Bell’s inequality.
• Anton Zeilinger meanwhile had already started using entanglement property to open up new technological possibilities. He demonstrated that it was possible to teleport the quantum states of particles to another location without the particle moving anywhere and without a medium.
• These experiments conducted by Clauser, Aspect and Zeilinger have decisively demonstrated that entanglement was real and in accordance with quantum theory and it was not being driven by any hidden forces as suggested by Einstein and others.

The satisfactory theoretical explanation of phenomenon, however, continue to elude scientists.

Application: The entanglement property is now being utilized to build the next generation of computers called quantum computers which exploit the quantum behaviour of particles to overcome the challenges considered unsurmountable. It is also being used for quantum cryptography.

Example Question:

What is Quantum Entanglement? How did the 2022 Nobel Prize winner contribute in the field of quantum entanglement. Discuss some of its key applications [15 marks, 250 words]

C)  Quantum Cryptography

About Quantum Cryptography: It is a protocol to distribute secret keys using the principles of quantum mechanics. It is a new technique that ensures the confidentiality of information transmitted between two parties, by exploiting counter intuitive behavior of elementary particles called as photons.

How Quantum Mechanics is used – Heisenberg’s Uncertainty Principle

The security of the quantum key distribution is guaranteed by the laws of quantum physics.

• Following uncertainty principle, an eavesdropper cannot know everything about a photon that carries a bit and will destroy a part of the information. Hence eavesdropping causes errors in transmission line, which can be detected by Alice (sender) and Bob (Receiver).
• If an eavesdropper, tries to determine the key, she will be detected. The legitimate parties will then discard the key, while no confidential information has been transmitted yet. If, on the other hand, no tapping is detected, the secrecy of the distributed key is guaranteed.

Other advantages of Quantum Cryptography/Quantum Key Distribution?

• It can distribute long key as often as possible between Sender and Receiver
• Long term secrecy of confidential data transmission