Question 1

Quantum tunnelling and quantisation only occur at the microscopic scale of single atoms or subatomic particles.

Accepted Answer

The 2025 Nobel laureates definitively proved that a macroscopic superconducting circuit containing billions of paired electrons can undergo quantum tunnelling and exhibit quantised energy states.

Question 2

The 2025 Nobel Prize in Physics was awarded for discovering the quantum tunnelling effect.

Accepted Answer

The prize was awarded specifically for discovering MACROSCOPIC quantum tunnelling in a collective electrical circuit, not the fundamental quantum tunnel effect itself, which was known for decades.

Question 3

Consider the following statements regarding the 2025 Nobel Prize in Physics:
1. The prize was awarded for the initial theoretical prediction of the Josephson effect in superconducting materials.
2. The laureates demonstrated that a macroscopic electrical system consisting of billions of Cooper pairs could exhibit discrete, quantised energy levels.
3. The groundbreaking experiments that led to this award were conducted using highly shielded superconducting electrical circuits in the 1980s.
How many of the above statements are correct?

Accepted Answer

(b) Only two — Statement 1 is incorrect. The 2025 Nobel Prize was awarded to Clarke, Devoret, and Martinis for macroscopic quantum tunnelling and energy quantisation. The theoretical prediction of the Josephson effect was made by Brian Josephson, who won the Nobel Prize in 1973. Statements 2 and 3 are correct; the laureates used superconducting circuits in 1984-1985 to prove that a macroscopic system of Cooper pairs can act as a single quantum particle with discrete energy levels.

Question 4

Match List I (Concept/Component related to the 2025 Nobel Prize) with List II (Its description/role):
List I:
A. Cooper pairs
B. Josephson junction
C. Circuit QED
D. Thermal noise

List II:
1. A component comprising two superconductors separated by a thin insulator, crucial for the tunnelling experiment.
2. The environmental interference that the laureates had to rigorously filter out to preserve quantum coherence.
3. The collective charge carriers in the superconductor that behaved in unison as a single quantum entity.
4. The field of study born from this discovery, essential for modern superconducting quantum computers.

Select the correct answer using the code given below:

Accepted Answer

(a) A-3, B-1, C-4, D-2 — Cooper pairs (A) are the paired electrons in a superconductor that act collectively (3). A Josephson junction (B) consists of superconductors separated by an insulator (1). Circuit Quantum Electrodynamics or Circuit QED (C) is the field that emerged from these discoveries, manipulating quantum information in circuits (4). Thermal noise (D) is the classical interference that masks macroscopic quantum effects and had to be filtered (2).

Question 5

Assertion (A): The discoveries by John Clarke, Michel H. Devoret, and John M. Martinis established the experimental foundation for modern superconducting quantum computers.
Reason (R): They successfully proved that an engineered, macroscopic electrical circuit can exhibit quantised energy states and tunnel through classically forbidden barriers without losing quantum coherence.
Select the correct answer:

Accepted Answer

(a) Both A and R are true and R is the correct explanation of A — Both statements are true. Because the laureates proved that a macroscopic, human-engineered circuit could maintain quantum states (quantisation and tunnelling) when properly isolated from noise (Reason), it became possible to use these circuits as reliable 'qubits' to store and manipulate quantum information, which is the exact hardware foundation of modern superconducting quantum computers (Assertion).