A BRIEF OVERVIEW OF THE PREVIOUS CLASS (05:07 PM)

BASICS OF QUANTUM TECHNOLOGY (05:09 PM)

• Photoelectric effect-
• When the light fell on the metal then an electron came out, which means enough energy was provided by the light to escape the electron. And the light in its waveform can not give enough energy to the electron.
• So, Einstein proposed that Light behaves like a particle but sometimes it behaves like a wave. It is called Wave-particle duality.
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• A French scientist also proposed that Everything behaves like waves and particles, and it is not limited to light. In general, there is Dual nature in the universe. 
• Larger objects have very small wavelengths and can be neglected. For larger objects classical mechanics is enough and there is no need to apply Quantum mechanics. 
• For smaller atoms, like electrons, behaves in dual nature. In general, there is dual nature in the universe. 
• Heisenberg uncertainty- 
• There are certain parameters/ quantities about an object that can not be measured simultaneously. 
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• Schrodingers Atomic model 
• In classical physics, everything is deterministic. In quantum mechanics everything is probabilistic. 
• When the Schrodinger equation is solved, the deterministic solution can not be found. It tells about the two possibilities of finding electrons.  
• When one is not measuring then the electron can be at both the place
• Quantum means- a set of postulates which aims to explain nature at a very elementary scale
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• Young's double-slit experiment
• [* Constructive interference- When two waves are meeting with each of their maxima and minima then the amplitude will increase. And the opposite is destructive interference]
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• When there was a sensor kept to measure nature then light behaved as a particle. 
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QUANTUM TECHNOLOGIES (05:57 PM)

• Quantum technologies are based on postulates of quantum mechanics which aim to explain the behaviour of nature at very smaller scales such as atoms, molecules, and elementary particles among others. 
• Following are the major domains of Quantum technologies. 
• Quantum computing. 
• Quantum communication.
• Quantum simulation. 
• Quantum metrology. 
• Quantum materials and devices. 

QUANTUM COMPUTING (06:04 PM)

• Context- Recently the government announced the National Quantum mission with a budget of 6000 cr rupees to be implemented by the Department of Science and Technology. 
• In Quantum computers rather than using binary units or Bits (0 and 1), Quantum bits or Qubits are used. Qubits is a superposition of 0 and 1 i.e. it can be any combination of 0 and 1 with different probability.
• Qubits can also be entangled in a way that changing one Qubit automatically changes other Qubits. This allows Quantum computers to perform operations on many qubits at once which leads to faster computation. 
• By using the principles of superposition and entanglement we can design a quantum computer which allows exponential use in the computational capacity as the number of Qubits increases. 
• Superposition is the ability of qubits to be in different states simultaneously, allowing them to work on a million computations at the same time.
• Entanglement is the ability of two or more quantum systems to become entangled irrespective of how far apart they are. The correlation between the entangled qubits gives information about the other qubit.

APPLICATIONS (07:07 PM)

• Cryptography- Quantum computing has the potential to break many of the encryption schemes currently used in communication and data storage. 
• Quantum simulation- WIth the help of quantum computers we can simulate complex chemical reactions or behaviour of microscopic particles which can be used for drug discovery, finding new types of fertilizers, Pesticides, and high-temperature superconductors among others. 
• It has applications in finance. For example- Risk management, Financial Strategies. 
• The term Quantum supremacy signifies that the quantum computer can solve a problem much faster than the fastest supercomputer on the planet. In 2017, google achieved Quantum supremacy with its quantum computer sycamore for one problem. 

CHALLENGES (07:24 PM)

• Quantum Decoherence- It is the tendency of Qubits to lose their quantum information. This can lead to errors in computation. 
• Qubits are very sensitive and often Quantum computers have to be kept at very low temperatures in isolated conditions.  
• Developing software and algorithms for quantum computing is still in its early stages similarly, there are hardware challenges. For example- We still do not know the best way to make a qubit. 
• Scalability- To solve real-life problems we need quantum computers with 1000s of Qubits, however, as of now, IBM has the largest Quantum computers in terms of Qubits with 433 qubits. 
• Quantum computers are very expensive to build and operate. 

QUANTUM COMMUNICATION (07:38 PM)

• Traditional data security realizes certain mathematical problems which can not be solved in real-time even by a very powerful supercomputer. For example- in Public key distribution data is encrypted with the help of a simple mathematical problem such as multiplying two large prime numbers. However, If an eavesdropper tries to decrypt data they will have to solve difficult problems such as finding prime factors of a sufficiently large no. 
• This problem can be solved by a powerful quantum computer thus we have to find ways to encrypt data that even quantum computers can not break. One such example is quantum key distribution
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• In QKD, the sender and receiver share a key with the help of entangled photons, if an eavesdropper attempts to listen to the conversation, will have to measure the quantum state of the photon, however, this changes the quantum state which alerts both sender and receiver to the presence of an eavesdropper. 
• DRDO and ISRO, have achieved QKD across a few KM channels.

QUANTUM METROLOGY (07:51 PM)

• Metrology is the science of accurate measurement. Quantum sensors are being used for measurement at a very smaller scale and they provide the most accurate measurement compared to other methods. 
• This has lots of applications in scientific experiments. 

The Topic for the next class:- Blockchain, cryptocurrency and the internet.