From UPSC perspective, the following things are important :

**Prelims level: **Qubit, superposition.

**Mains level: **Paper 3- What do you understand by quantum technology? What are its applications? How it is different from the classical computer technology?

The article suggests that the corona crisis would speed up research in the field of quantum computing. The tremendous speed offered by quantum computers will help us find a cure for diseases like Covid-19 in a much shorter duration. This article explains the limitations of classical computers, working of quantum technology, and how quantum computer overcomes these limitations.

#### Use of supercomputer to find the cure of Covid-19

- The whole world is pressurized into quickly discovering a vaccine and a cure for covid-19.
**IBM’s Summit,**the world’s fastest supercomputer, was used for running numerous simulations and computations.- These
**simulations and computations**help scientists find promising molecules to fight the pandemic. - The latest update says the Summit has been able to identify 77 candidate molecules that researchers can use in trials.
- This was achieved in
**just two days**, while, traditionally, it has taken months to make such progress.

#### Computing capacity as a limit on molecular discoveries

- Today, faster molecular discoveries are limited by computing capacity.
- Molecular discoveries are also limited by the need for scientists to write codes for
**harnessing**the computing power. - It is no secret that classical
**computing power is plateauing (**e. it is not growing anymore**)** - And till we have scalable
**artificial intelligence (AI)**and**machine learning (ML),**scientists will have to**write code for not only different scenarios**but also for**different computing platforms.** - So, what we need today is more computing power.

The following points explain the limits of classical computers. Pay attention to the Moore’s law, and how it explains the development of semiconductor technologies and in turn computers as a whole.

#### What is the solution to the limits of classical computers?

- Given that we have already
**neared the peak of classical computing**, the solution probably is quantum computing. - Not just vaccines, quantum computing can accelerate many innovations, such
**as hyper-individualized medicines**,**3-D printed organs**,**search engines**for the physical world etc. - All innovations currently constrained by the
**size of transistors**used in**classical computing**chips can be unleashed through**quantum computing.** **Moore’s law:**In 1965, Gordon Moore had said**the number of transistors that can be packed into a given unit of space will double about every two years.**- Subsequently, in an interview in 2005, he himself admitted that this law can’t continue forever.
- He had said: “It is the nature of exponential functions, they eventually hit a wall.”
- Over the last 60 years, we reaped the benefits of Moore’s law in many ways.
- For instance, compared to initial days of the Intel 4004, the modern 14nm processors deliver way bigger impact—
**3,500 times better performance**and 90,000 times improved efficiency,**at 1/60,000th the cost!** - Yet, we are also seeing his 2005 statement coming true. All the experts agree that the ‘wall’ is very near.
- So, what next? The answer again is probably the same—quantum computing.

Quantum technology is one of the emerging and revolutionary technologies, you should be aware of the terms and general principle which lies at the heart of such technology. So, terms like superposition, qubit, binary etc are important if you want to answer a questions related to this technology.

#### Quantum computing and its applications

- It is
**no more a concept**, there are working models available on the cloud. **How it works:**Quantum computing uses the ability of sub-atomic particles to exist in multiple states simultaneously,**until it is observed.****The concept of qubits:**Unlike classical computers that can store information in just two values,**that is 1 or 0**, quantum computing uses qubits that can exist in any**superposition**of these values,- This superposition enables quantum computers to solve in seconds problems which a classical computer would take thousands of years to crack.
**Applications**: The application of this technology is enormous, and just to cite a few, it can help with the discovery of new molecules, optimize financial portfolios for different risk scenarios.- It can also crack RSA encryption keys, detect stealth aircraft, search massive databases in a split second and truly enable AI.

#### Investment in the development of technology

- In the Union budget this year, the Indian government announced
**investments of ₹8,000 crores**for developing quantum technologies and applications. - Globally, too, countries and organizations are rushing to develop this technology and have already invested enormous capital towards its research.

#### Conclusion

Historically, unprecedented crises have always created more innovations than routine challenges or systematic investments. Coincidentally, current times pose similar opportunities in disguise for the development of quantum technologies.

#### Back2Basics: Difference between bit and qubit

**A binary digit**, characterized as**0 and 1**, is used to represent information in classical computers.- A binary digit can represent up to one bit of information, where a bit is the basic unit of information.
- In classical computer technologies, a processed bit is implemented by one of two levels of low DC voltage.
- And whilst switching from one of these two levels to the other, a so-called
**forbidden zone**must be passed as fast as possible, as electrical voltage cannot change from one level to another instantaneously. - There are two possible outcomes for the measurement of a qubit—usually taken to have the value “0” and “1”, like a bit or binary digit.
- However, whereas the state of a bit can only be either 0 or 1, the general state of a qubit according to quantum mechanics can be a
**coherent superposition of both.** - Moreover, whereas a measurement of a classical bit
**would not disturb its****state**, a measurement of a qubit**would destroy its coherence**and irrevocably disturb the**superposition state**. - It is possible to fully encode one bit in one qubit.
- However, a qubit can hold more information, e.g. up to two bits using superdense coding.
- For a system of n components, a complete description of its state in classical physics requires only n bits, whereas in quantum physics it requires 2n−1 complex numbers.

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