In News:

• Recently, 3 scientists - Frenchman Alain Aspect, American John F Clauser and Austrian Anton Zeilinger, jointly won the 2022 Nobel Prize in physics for their work on quantum information science - a field with significant applications, including in encryption.
• They found how unseen particles, like photons, can be linked or entangled with each other even when separated by great distances, a field that alarmed Albert Einstein, who described it in a letter as "spooky action at a distance."

What’s in today’s article:

• About quantum technology
• About the work of Nobel Prize-winning scientist

Quantum technology:

Background:

• According to classical physics (based on Newtonian Mechanics), two objects cannot occupy the same space at the same moment.
• Until the early 20th century, it was thought that this was a fundamental physics law that was followed by everything in nature.
• However, scientists began to investigate particles such as atoms, electrons and light waves, which did not appear to fit these laws.
• In an attempt to examine the "quirky" principles that did bind such particles, the subject of quantum mechanics was founded by Max Planck, Neils Bohr and Albert Einstein.

About:

• It is a class of technology (developed in the early 20th century) that works by using the principles of quantum mechanics - the physics of subatomic particles, including quantum entanglement and quantum superposition.
• Hence, it is based on phenomena exhibited by microscopic particles (like photons, electrons, atoms etc) which are quite distinct from the way normal macroscopic objects behave.

The principles behind quantum technology:

• Quantum entanglement:
  • Despite being separated, when two atoms are connected or entangled, the phenomenon is known as quantum entanglement.
  • If the properties of one of the atom changes, the other changes instantly and quantum mechanics observe these changes in the properties.
  • It enhances the security of communication through quantum protected encrypted keys, as entangled atoms can be used to detect whether the transmission of data has been breached by someone.
• Quantum superposition:
  • The theory that subatomic particles exist in multiple states simultaneously is known as quantum superposition.
  • The practical application of this principle is in quantum computers.
  • While digital computers store data as bits (binary of 0 & 1), quantum computers use qubits that exist as a 1, 0 or both at the same time.
  • This superposition generates an almost endless set of options which enables unbelievably fast calculations.

Applications:

• Quantum technology promises improvements to a vast range of everyday gadgets, including:
  • More reliable navigation and timing systems.
  • More secure communications.
  • More accurate healthcare imaging through quantum sensing (using quantum phenomenon to perform a measurement of a physical quantity).
  • More powerful computing - quantum computers.
• In disaster management through better prediction, computing, etc.
• To understand biological phenomena such as smell, consciousness and to understand the spread of pandemics like Covid-19, etc.

The work of Nobel Prize-winning scientist:

Background:

• Quantum mechanics permits two or more particles to be in an entangled state leading to coordination between these particles. Initially, this was thought to be a result of hidden variables.
• However, John Stewart Bell discovered in the 1960s that there are no hidden variables at work. In reality, coordination between entangled particles is a matter of chance when measuring the properties of one of the particles.
• Bell developed a mathematical inequality that says, “if there are hidden variables, the correlation between the results of a large number of measurements will never exceed a certain value”.
• However, quantum mechanics demonstrates that this value can be exceeded, resulting in a stronger correlation between the results than is feasible with hidden variables.
• Exceeding this figure demonstrates that there is no mysterious "spooky action" and that the world is regulated by quantum mechanics.

About this year’s work:

• Over a span of several decades, this year’s Nobel laureates have built on Bell’s work.
• American physicist John Clauser developed a realistic experiment by passing entangled photons through polarisation filters (commonly used in sunglasses to block light at certain angles) to test Bell’s inequality.
  • His experiments showed a clear violation of Bell’s inequality, confirming that there were no hidden variables at play.
  • Clauser's experiment, however, had limitations as the settings for detecting the entangled photons were fixed, which meant that the experimental setup itself might have been unable to detect some particles controlled by hidden factors.
• Alain Aspect, a French physicist, attempted to construct an experiment that eliminated this possible bias by altering the measurement settings only after the entangled photons had left their source, so that the setup did not influence the results.
• Anton Zeilinger, an Austrian physicist, was among the first to investigate quantum systems with more than two entangled particles, which currently serve as the foundation for quantum computation and allow entangled particles to be manipulated.
  • Among his most famous accomplishments was the discovery of quantum teleportation, which allows particles to acquire previously unknown quantum properties from other particles over large distances.

Significance:

• The first quantum revolution resulted in the development of transistors and lasers.
• The ability to handle and manipulate systems of entangled particles will provide researchers with improved tools to create quantum computers, improve measurements, develop quantum networks and establish secure quantum encrypted communication.
• Quantum computers can execute complicated calculations that are considerably above the capabilities of traditional computers.
  • Quantum computing has already shown potential in chemical and biological engineering, as well as cybersecurity.
  • Computing systems that can manage enormous datasets and execute complicated simulations will also aid areas such as artificial intelligence and Big Data.