GS Notes

19. Science and Technology Notes 11

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Elaborate Notes

Basics of Quantum Technology

  • Photoelectric Effect and Wave-Particle Duality

    • Historical Context: The phenomenon was first observed by Heinrich Hertz in 1887 during his experiments with electromagnetic waves. However, classical physics, which described light purely as a wave, could not explain the observations, such as the instantaneous emission of electrons and the dependence of electron energy on light frequency, not intensity.
    • Planck’s Contribution (1900): Max Planck, while studying black-body radiation, proposed that energy is not continuous but is emitted or absorbed in discrete packets, which he called “quanta”. The energy of a quantum was given by E = hν (where ‘h’ is Planck’s constant and ‘ν’ is the frequency).
    • Einstein’s Explanation (1905): Albert Einstein extended Planck’s idea to light itself, proposing that light consists of particles called “photons”. He explained the photoelectric effect by stating that a single photon transfers its entire energy to a single electron in a metal. If this energy is greater than the metal’s “work function” (the minimum energy required to free an electron), the electron is ejected. This explanation, for which he won the Nobel Prize in Physics in 1921, established that light has a particle-like nature.
    • De Broglie’s Hypothesis (1924): French physicist Louis de Broglie, in his PhD thesis, postulated that the wave-particle duality is a universal principle, applying not just to light but to all matter. He proposed that any moving particle has an associated wave, with a wavelength (λ) given by λ = h/p (where ‘p’ is the momentum of the particle).
    • Experimental Verification: The wave nature of electrons was experimentally confirmed by Clinton Davisson and Lester Germer in 1927 in the United States, and independently by George Paget Thomson in the UK, through electron diffraction experiments. This proved de Broglie’s hypothesis and solidified the concept of universal wave-particle duality. For macroscopic objects, the wavelength is so minuscule that its wave properties are negligible, and classical mechanics suffices.

  • Heisenberg’s Uncertainty Principle

    • Formulation: Proposed by Werner Heisenberg in 1927, this principle is a fundamental tenet of quantum mechanics. It states that there is a fundamental limit to the precision with which certain pairs of complementary physical properties of a particle, known as conjugate variables, can be known simultaneously.
    • Core Idea: The most common pair of such variables is position (x) and momentum (p). The principle mathematically states that the product of the uncertainties in their measurement (Δx * Δp) must be greater than or equal to a constant value (ħ/2, where ħ is the reduced Planck’s constant).
    • Implication: This is not a limitation of our measuring instruments but an inherent property of quantum systems. The more precisely one property is measured, the less precisely the other can be determined. For instance, to locate an electron with high precision, one must use high-energy (short-wavelength) photons, which in turn impart a large, uncertain momentum to the electron.

  • Schrödinger’s Atomic Model and Probabilistic Nature

    • The Schrödinger Equation (1926): Erwin Schrödinger developed a wave equation that describes how the quantum state of a physical system changes over time. Unlike classical physics, which is deterministic (predicting a precise outcome), the solutions to the Schrödinger equation are “wave functions” (represented by ψ).
    • Probabilistic Interpretation: The wave function itself is not directly observable. However, its square (|ψ|²) gives the probability density of finding a particle at a particular point in space at a given time. This introduced a fundamental probabilistic nature into physics. Instead of fixed orbits for electrons as in the Bohr model, Schrödinger’s model describes “orbitals,” which are regions of high probability for finding an electron.
    • Schrödinger’s Cat: This is a famous thought experiment devised by Schrödinger in 1935 to illustrate the paradoxical nature of quantum superposition. A cat in a sealed box is linked to a quantum event (like the decay of a radioactive atom). Until the box is opened and an observation is made, the cat is considered to be in a superposition of being both alive and dead simultaneously. This highlights the counter-intuitive shift from a probabilistic quantum state to a definite classical outcome upon measurement.

  • Young’s Double-Slit Experiment

    • Classical Experiment (1801): Thomas Young first performed this experiment with light, demonstrating that when light passes through two closely spaced slits, it creates an interference pattern of bright and dark fringes on a screen behind it. This was considered definitive proof of the wave nature of light.
    • Quantum Version: The experiment was later conceptually adapted for particles like electrons. When electrons are fired one by one towards a double slit, they still collectively form an interference pattern, as if each electron passed through both slits simultaneously as a wave and interfered with itself.
    • The Observer Effect: The most profound aspect is that if a detector is placed at the slits to determine which slit each electron passes through, the interference pattern disappears. The electrons then behave like classical particles, creating two distinct bands on the screen. This act of measurement or observation forces the quantum system to “choose” a definite state (particle-like) and collapses its wave-like superposition, demonstrating the intimate role of the observer in quantum reality.

Quantum Technologies

Quantum technologies are a class of technologies that harness the principles of quantum mechanics, particularly superposition and entanglement, to achieve capabilities far beyond those of classical technologies.

  • Quantum Computing:

    • Core Unit (Qubit): Classical computers use bits (0 or 1). Quantum computers use quantum bits or ‘qubits’. A qubit can exist not only as 0 or 1 but also in a superposition of both states simultaneously. This is often represented as α|0⟩ + β|1⟩, where α² and β² are the probabilities of the qubit being 0 or 1 upon measurement.
    • Superposition: This property allows a quantum computer with ‘n’ qubits to exist in 2^n states at once, enabling massive parallel computation.
    • Entanglement: Described by Einstein as “spooky action at a distance,” entanglement is a quantum phenomenon where two or more qubits become linked in such a way that their fates are intertwined, regardless of the distance separating them. Measuring the state of one entangled qubit instantaneously influences the state of the other(s). This correlation is a crucial resource for quantum algorithms and communication.
    • National Quantum Mission (NQM): In the Union Budget 2023-24, the Government of India announced the NQM with an outlay of ₹6003.65 crore for a period of eight years (2023-31). It is implemented by the Department of Science and Technology (DST) and aims to seed, nurture, and scale up scientific and industrial R&D and create a vibrant quantum technology ecosystem in India.

  • Quantum Communication:

    • Principle: This field uses quantum phenomena to secure communication. Its most prominent application is Quantum Key Distribution (QKD).
    • Quantum Key Distribution (QKD): Classical cryptography, like the RSA algorithm (Rivest-Shamir-Adleman, 1977), relies on computational difficulty (factoring large prime numbers). A sufficiently powerful quantum computer could break these codes using Shor’s algorithm (Peter Shor, 1994). QKD, in contrast, is based on the laws of physics.
    • Mechanism: In a typical QKD protocol like BB84 (Charles Bennett and Gilles Brassard, 1984), a secret key is encoded onto individual photons. According to the uncertainty principle and the no-cloning theorem, any attempt by an eavesdropper to intercept and measure these photons will invariably disturb their quantum state. This disturbance is detectable by the legitimate users (sender and receiver), who can then discard the compromised key and create a new one.
    • Indian Efforts: The Defence Research and Development Organisation (DRDO) and the Indian Space Research Organisation (ISRO) have successfully demonstrated QKD over terrestrial and satellite links, respectively, showcasing indigenous capability.

  • Quantum Metrology and Sensing:

    • Metrology: This is the science of measurement. Quantum metrology leverages quantum effects to make measurements with unprecedented precision and sensitivity, surpassing the limits of classical methods.
    • Applications:
      • Atomic Clocks: These are the most accurate timekeeping devices, using the resonant frequency of atoms (like Caesium-133) as their pendulum. They are a primary example of quantum metrology.
      • Quantum Sensors: Can detect minute changes in magnetic fields (magnetometers for medical imaging or navigation), gravity (gravimeters for geological surveying), and rotation (gyroscopes).
      • Scientific Experiments: Essential for high-precision experiments like detecting gravitational waves at LIGO (Laser Interferometer Gravitational-Wave Observatory).

  • Other Domains:

    • Quantum Simulation: Using a controllable quantum system to simulate the behavior of other, more complex quantum systems. This is invaluable for materials science (e.g., designing high-temperature superconductors) and drug discovery (simulating molecular interactions).
    • Quantum Materials and Devices: Developing new materials with unique quantum properties (e.g., topological insulators, 2D materials like graphene) and fabricating devices like single-photon detectors and sources for quantum applications.

Applications and Challenges of Quantum Computing

  • Applications:

    • Cryptography: While it poses a threat to current encryption (e.g., Shor’s algorithm breaking RSA), it also enables secure communication through QKD.
    • Healthcare and Drug Discovery: Simulating complex molecules and their interactions can drastically accelerate the development of new drugs and personalized medicine.
    • Financial Modelling: Optimizing financial strategies, pricing complex derivatives, and managing risk with greater accuracy.
    • Advanced Materials: Designing novel materials with desired properties, such as more efficient catalysts for fertilizers or better batteries.
    • Quantum Supremacy: A term signifying the point where a quantum computer can perform a specific calculation that is practically impossible for even the most powerful classical supercomputer. Google claimed to have achieved this in 2019 with its 53-qubit Sycamore processor, by performing a task in 200 seconds that would have taken a supercomputer an estimated 10,000 years.

  • Challenges:

    • Quantum Decoherence: Qubits are extremely fragile. Their quantum state (superposition and entanglement) is easily disturbed by interactions with the environment (e.g., heat, vibrations, electromagnetic fields), a process called decoherence. This leads to the loss of quantum information and introduces errors into computations.
    • Error Correction: Due to decoherence, quantum error correction is far more complex than in classical computers. It often requires a large number of physical qubits to create a single, stable ‘logical qubit’.
    • Hardware and Scalability: Building and controlling a large number of stable, high-quality qubits is a major engineering hurdle. Current systems, like IBM’s 433-qubit ‘Osprey’ processor, are significant achievements but are still far from the thousands or millions of qubits needed for fault-tolerant quantum computing.
    • Extreme Operating Conditions: Most current quantum computers require near-absolute zero temperatures (-273°C) and shielding from all external interference, making them expensive and difficult to maintain.
    • Software and Algorithms: The development of quantum algorithms and software is still in its infancy. New programming languages and compilers are needed to harness the power of quantum hardware effectively.

Prelims Pointers

  • Photoelectric Effect: Explained by Albert Einstein (1905), demonstrating the particle nature of light (photons).
  • Wave-Particle Duality: Proposed for all matter by Louis de Broglie (1924).
  • Heisenberg’s Uncertainty Principle (1927): States that conjugate variables like position and momentum cannot be measured simultaneously with perfect accuracy.
  • Qubit (Quantum Bit): The basic unit of quantum information. Can exist in a superposition of 0 and 1.
  • Superposition: The ability of a quantum system to be in multiple states at the same time until it is measured.
  • Entanglement: A state where two or more qubits are linked, and the state of one instantly affects the others, regardless of distance.
  • Quantum Decoherence: The loss of quantum properties in a qubit due to interaction with its environment, leading to computational errors.
  • Quantum Supremacy: The demonstrated ability of a quantum computer to solve a problem that no classical computer can solve in any feasible amount of time. Google’s ‘Sycamore’ processor achieved this in 2019.
  • Quantum Key Distribution (QKD): A secure communication method that uses quantum mechanics to encrypt and share a key. Any eavesdropping attempt is detectable.
  • National Quantum Mission (NQM):
    1. Launched by the Government of India.
    2. Outlay: ₹6003.65 crore.
    3. Duration: 2023-2031.
    4. Implementing Agency: Department of Science and Technology (DST).
  • Shor’s Algorithm: A quantum algorithm for integer factorization, which poses a threat to current public-key cryptography systems like RSA.
  • Indian organisations working on Quantum Technology include DRDO, ISRO, Raman Research Institute (RRI), and various IITs.

Mains Insights

GS Paper III: Science & Technology, Indian Economy, Security

  1. Transformative Economic Potential:

    • Cause-Effect: Investment in quantum R&D (like the NQM) can lead to the development of disruptive technologies. This can create new industries in drug discovery, materials science, and finance, boosting GDP and creating high-skilled jobs.
    • Analysis: India’s NQM is a strategic move to avoid being left behind in the “second quantum revolution.” Success will depend on bridging the gap between academic research and industrial application, fostering startups, and developing a skilled workforce. The mission’s focus on creating thematic hubs is a positive step towards creating a collaborative ecosystem.

  2. National Security Implications:

    • Threat: The advent of fault-tolerant quantum computers poses a direct threat to the cryptographic systems that protect sensitive government, military, and financial data. All currently encrypted data could potentially be decrypted retroactively.
    • Opportunity: Developing sovereign capability in quantum communication (like QKD) and post-quantum cryptography (PQC) is crucial for securing strategic communications. This is a key driver for initiatives by DRDO and ISRO.
    • Debate: There is a debate between the utility of QKD (secure but requires specialized hardware and has distance limitations) and PQC (software-based solutions that can run on existing infrastructure but rely on computational hardness). A hybrid approach is likely the future.

  3. Challenges in Building an Indigenous Quantum Ecosystem:

    • Hardware and Fabrication: India currently lacks the advanced semiconductor fabrication facilities (fabs) needed to build cutting-edge quantum processors. This creates a dependency on foreign hardware.
    • Human Resources: There is a global shortage of quantum experts. India needs to rapidly scale up its education and training programs at the PhD and postdoctoral levels to create the necessary talent pool.
    • Investment: While the NQM is a significant step, sustained and large-scale private sector investment is crucial for commercialization, which is currently lagging compared to the US and China.

GS Paper IV: Ethics, Integrity, and Aptitude

  1. Dual-Use Dilemma:

    • Quantum computing is a classic example of a dual-use technology. The same capabilities that can be used to design life-saving drugs can also be used to design more powerful weapons or break global financial systems. This raises ethical questions about the direction and control of research.
    • Ethical Responsibility: Scientists and policymakers have an ethical responsibility to establish international norms and safeguards to prevent the misuse of quantum technologies, particularly in surveillance and warfare.

  2. Equity and Access:

    • The immense cost and complexity of quantum computing could lead to a “quantum divide,” where only wealthy nations and corporations can access its benefits. This could exacerbate existing global inequalities.
    • Policy Imperative: Ethical governance frameworks should promote equitable access to the benefits of quantum technology, for instance, through cloud-based platforms for researchers in developing countries.

Previous Year Questions

Prelims

  1. Which one of the following is the context in which the term “qubit” is mentioned? (UPSC CSE 2022) (a) Cloud Services (b) Quantum Computing (c) Visible Light Communication Technologies (d) Wireless Communication Technologies

    Answer: (b) Quantum Computing. A qubit, or quantum bit, is the basic unit of quantum information in quantum computing.

  2. With reference to “Near Field Communication (NFC) Technology”, which of the following statements is/are correct? (UPSC CSE 2015 - Illustrative of S&T questions)

    1. It is a contactless communication technology that uses electromagnetic radio fields.
    2. NFC is designed for use by devices which can be at a distance of even a metre from each other.
    3. NFC can use encryption when sending sensitive information. Select the correct answer using the code given below. (a) 1 and 2 only (b) 3 only (c) 1 and 3 only (d) 1, 2 and 3

    Answer: (c) 1 and 3 only. NFC is a very short-range technology, typically a few centimeters, not a metre. Statement 2 is incorrect.

  3. Consider the following statements: (UPSC CSE 2020)

    1. The Nobel Prize in Physics for 2020 was jointly awarded to Roger Penrose, Reinhard Genzel and Andrea Ghez for their discoveries about black holes.
    2. The discovery of gravitational waves by LIGO was a significant achievement in the field of astrophysics. Which of the statements given above is/are correct?

    Answer: (This question is illustrative of how UPSC asks about Nobel prizes and major scientific discoveries, a category under which quantum technology could fall.) Both statements are correct. High-precision measurements, like those at LIGO, often rely on principles related to quantum metrology (e.g., controlling quantum noise).

  4. The term ‘Public Key Infrastructure’ is used in the context of: (UPSC CSE 2020) (a) Digital security infrastructure (b) Food security infrastructure (c) Health care and education infrastructure (d) Telecommunication and transportation infrastructure

    Answer: (a) Digital security infrastructure. This is relevant as quantum computers threaten to break the public-key cryptography that underpins this infrastructure.

  5. Which of the following is/are the application(s) of Somatic Cell Nuclear Transfer (SCNT) technology? (UPSC CSE 2017 - Illustrative of application-based S&T questions) (a) Reproductive cloning of animals (b) Production of biolarvicides (c) Manufacture of biodegradable plastics (d) Production of organisms free of diseases

    Answer: (a) Reproductive cloning of animals. This type of question shows the UPSC’s focus on the applications of emerging technologies. A similar question could be framed for quantum computing’s applications in drug discovery or material science.

Mains

  1. What is the main task of the Department of Science and Technology in India? What are the major achievements of the Department of Science and Technology in the field of Space Technology? (UPSC CSE 2021, 15 marks)

    Answer Outline:

    • Introduction: Briefly state the mandate of the DST as the nodal agency for formulating and implementing S&T policies and promoting R&D.
    • Main Tasks of DST:
      • Policy formulation for Science and Technology.
      • Promotion of new areas of S&T with a focus on emerging technologies (mentioning the National Quantum Mission as a recent example).
      • Coordination of S&T activities and fostering collaborations.
      • Funding R&D in academic institutions and labs.
      • Promoting science popularization and developing scientific temper.
    • Role in Space Technology: Clarify that while ISRO (under the Department of Space) is the primary agency, DST plays a crucial supporting and foundational role by funding basic research in physics, material science, and astronomy in universities and institutes like the Indian Institute of Astrophysics, which contributes to the space program’s knowledge base. It also supports the development of instruments and ancillary technologies used in space missions through various research grants. [Note: The question’s second part is slightly misdirected as DoS/ISRO is the main body, but DST’s supportive role should be explained].
    • Conclusion: Conclude by summarizing DST’s pivotal role in creating a broad scientific ecosystem that indirectly and directly strengthens specialized fields like space technology.

  2. What do you understand by the term ‘disruptive technology’? Discuss the potential of quantum computing to be a disruptive technology and the challenges India faces in its development. (UPSC Style Question, 15 marks)

    Answer Outline:

    • Introduction: Define disruptive technology as an innovation that significantly alters the way consumers, industries, or businesses operate, often displacing established technologies and creating a new market.
    • Quantum Computing as a Disruptive Technology:
      • Cryptography & Security: It can break current encryption standards, disrupting global security.
      • Healthcare: Can revolutionize drug discovery and genomics by simulating molecules, making the current trial-and-error process obsolete.
      • Finance: Can create new high-frequency trading and risk analysis models, disrupting financial markets.
      • Materials Science: Can lead to the design of novel materials (e.g., room-temperature superconductors), disrupting energy and manufacturing sectors.
    • Challenges for India:
      • Technological & Infrastructure Gap: Lack of advanced fabrication labs, need for extreme-cold infrastructure.
      • Human Capital: Scarcity of trained quantum physicists and engineers.
      • Financial Investment: High cost of R&D and need for greater private sector participation despite the NQM.
      • Ecosystem Development: Need for stronger academia-industry collaboration to translate research into commercial products.
    • Conclusion: Conclude that while the challenges are significant, the strategic importance of quantum computing makes overcoming them a national priority, and the National Quantum Mission is a critical step in this direction.

  3. The Government of India has launched the National Quantum Mission. In this context, discuss the significance of this mission for India’s strategic autonomy and economic development. (UPSC Style Question, 10 marks)

    Answer Outline:

    • Introduction: Briefly mention the launch of the National Quantum Mission (NQM) and its objective to position India as a leading nation in the development of Quantum Technology.
    • Significance for Strategic Autonomy:
      • National Security: Developing indigenous QKD and post-quantum cryptography will secure military and critical infrastructure communications from future threats.
      • Reduced Dependence: Prevents dependence on other nations for a critical, next-generation technology, which could be subject to controls or denial.
      • Geopolitical Standing: Leadership in quantum tech enhances India’s global stature and role in international S&T collaborations.
    • Significance for Economic Development:
      • New Industries: Fosters startups and industries in quantum computing, sensing, and communication.
      • Competitive Advantage: Provides a competitive edge to key sectors like pharmaceuticals, finance, and manufacturing through quantum applications.
      • Job Creation: Creates demand for a new class of highly skilled professionals, boosting the knowledge economy.
    • Conclusion: NQM is a vital strategic investment that can ensure India’s security and propel its economic growth in the 21st century by building self-reliance in a foundational technology of the future.

  4. Discuss the principles of Superposition and Entanglement. How do these principles enable quantum computers to be more powerful than classical computers? (UPSC Style Question, 10 marks)

    Answer Outline:

    • Introduction: Start by stating that superposition and entanglement are two counter-intuitive principles of quantum mechanics that are harnessed to power quantum computers.
    • Principle of Superposition:
      • Explain that unlike a classical bit which is either 0 or 1, a qubit can be in a combination of both states simultaneously.
      • Use an analogy like a spinning coin being both heads and tails until it lands. This allows a quantum computer to process a vast number of possibilities at once.
    • Principle of Entanglement:
      • Explain it as a deep connection between two or more qubits. The state of one is intrinsically linked to the other, no matter how far apart they are.
      • Describe it as Einstein’s “spooky action at a distance.” This property allows for complex correlations and information processing that is impossible in classical systems.
    • How they enable power:
      • Massive Parallelism: Superposition allows an n-qubit register to represent 2^n values simultaneously, leading to an exponential increase in computational space.
      • Complex Algorithms: Entanglement is a crucial resource that is exploited by quantum algorithms like Shor’s (for factoring) and Grover’s (for searching) to solve specific problems much faster than any known classical algorithm.
    • Conclusion: Conclude that by leveraging superposition for parallelism and entanglement for complex correlations, quantum computers can tackle problems that are intractable for even the most powerful classical supercomputers.

  5. What is Quantum Key Distribution (QKD)? How does it provide a more secure method of communication compared to traditional cryptographic methods? (UPSC Style Question, 10 marks)

    Answer Outline:

    • Introduction: Define QKD as a technology that uses the principles of quantum mechanics to distribute a secret key for encrypting and decrypting messages between two parties.
    • How QKD works:
      • Explain the process: a sender (Alice) encodes bits of the key onto the quantum states (e.g., polarization) of single photons.
      • The receiver (Bob) measures these states to reconstruct the key.
      • They then compare a subset of the key over a public channel to detect errors or eavesdropping.
    • Superior Security compared to Traditional Methods:
      • Based on Laws of Physics: Traditional methods (like RSA) rely on the computational difficulty of solving mathematical problems. Their security is conditional and can be broken by future advances in computing (like quantum computers).
      • Detects Eavesdropping: QKD’s security is based on the fundamental principle that the act of measuring a quantum system disturbs it (Heisenberg’s Uncertainty Principle). If an eavesdropper (Eve) tries to intercept and measure the photons, she will inevitably introduce detectable anomalies. Alice and Bob will know the channel is compromised and can discard the key. This provides unconditional, physics-based security.
    • Conclusion: QKD offers a paradigm shift in security from computational hardness to physical law, making it a “future-proof” method for securing communication channels against both present and future threats, including those from quantum computers.

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