Majorana Zero Modes: Potential Breakthrough for Quantum Computing

Context:

Recently, researchers at Microsoft announced that they had figured out a way to create an elusive kind of particle that could potentially revolutionise quantum computing.

• The claim pertains to particles called Majorana zero modes, whose unique properties could help build quantum computers that are much less fragile than they are today, making them computationally superior.

Relevance:

GS III: Science and Technology

Dimensions of the Article:

1. Majorana Fermions and Majorana Zero Modes
2. Advantages of Majorana Zero Modes in Computing:
3. Topological Degeneracy
4. Advantages of Topological Quantum Computing:
5. Quantum Computing

Majorana Fermions and Majorana Zero Modes

Majorana Fermions:

• All subatomic particles that make up matter are called fermions.
• The Dirac equation, formulated in 1928, described the behavior of subatomic particles moving at near the speed of light.
• The equation predicted the existence of antiparticles for each particle, leading to the discovery of the positron in 1932.
• In 1937, Ettore Majorana found that particles satisfying certain conditions could be their own antiparticles, known as Majorana fermions.
• Neutrinos are believed to be potential Majorana fermions, but experimental proof is still lacking.

Majorana Zero Modes:

• All particles have four quantum numbers, including the quantum spin, which has half-integer values for fermions.
• Fermions can form bound states, and their total quantum spin must have a half-integer value.
• Bound states that are their own antiparticles are called Majorana fermions.
• When these bound states exist at zero energy, they are known as Majorana zero modes.
• Physicists have been searching for Majorana zero modes for over two decades.

Advantages of Majorana Zero Modes in Computing:

• Majorana zero modes are of great interest for their potential application in topological quantum computing, a more powerful form of quantum computing.
• Quantum computers utilize individual electrons as qubits, the fundamental units of information, by encoding information in properties such as spin.
• Quantum computers can access computational techniques and pathways not available to classical computers due to the quirky rules of quantum mechanics.
• Quantum superposition allows qubits to hold multiple values simultaneously, unlike classical bits that can only hold one value at a time.
• However, quantum computers are fragile and susceptible to decoherence, losing their quantum abilities with even slight disturbances.
• Majorana zero modes, which consist of an electron and a hole, offer a solution. They can be used as qubits in a quantum computer.
• Physicists have found that when the entities of a Majorana zero mode are separated, even if one entity is disturbed, the overall qubit remains protected and does not decohere.
• This protection of encoded information makes Majorana zero modes more robust and less prone to errors.
• In topological quantum computing, if there is no overlap between the two half-particles, a qubit based on Majorana zero modes can potentially exist indefinitely.

Topological Degeneracy:

• In topological systems, there can be multiple states or configurations at the lowest energy level, known as the ground state energy.
• This is different from typical systems where the ground state exists in a single configuration.
• Topological degeneracy refers to the presence of multiple possible states at the ground state energy level.
• Topology, the study of properties that remain unchanged under continuous deformations, plays a role in determining the topological properties of matter.
• For example, a rubber band that undergoes continuous deformation will always have one hole, while a pair of shorts will always have three holes.
• If two states, such as the rubber band and the shorts, are topologically different and exhibit topological degeneracy, they can represent two possible states of the same system in its ground state.
• The information can be stored in the different topological properties of these states, such as the number of holes.
• Majorana zero modes can serve as qubits in quantum computing and are less susceptible to information loss, making
• them valuable for building robust quantum computers.

Advantages of Topological Quantum Computing:

• Quantum computers based on Majorana zero modes can take advantage of non-Abelian statistics, a peculiar mathematical property that governs their behavior.
• Non-Abelian statistics means that the order in which tasks are performed can affect the outcomes.
• Algorithms running on a quantum computer using Majorana zero modes and following non-Abelian statistics can have an additional degree of freedom.
• This flexibility allows for new possibilities in computation, where rearranging the order of steps can lead to different results.
• Quantum computers with topological features can offer enhanced computational capabilities and novel approaches to solving problems.

Quantum Computing:

• Quantum computing is a field of computer science that utilizes the principles of quantum theory to process and manipulate information.
• Quantum theory describes the behavior of energy and matter at the atomic and subatomic levels.
• Quantum computers have the potential to solve complex problems by exploring and analyzing a vast number of possibilities simultaneously.

Working Principle:

• Quantum computers use qubits (quantum bits) instead of classical bits.
• While classical bits can only represent either a 0 or a 1, qubits can exist in a superposition, representing both 0 and 1 simultaneously until measured.
• Multiple qubits can also be entangled, meaning their states become interconnected and quantum mechanically linked.
• Qubits can be implemented using various physical systems, such as manipulating atoms, ions, electrons, or artificial atoms created through nanoengineering techniques like superconducting qubits.
• These physical systems allow for the control and manipulation of quantum states to perform computations.
• Quantum computers rely on principles like superposition, entanglement, and quantum interference to perform complex calculations efficiently.

-Source: The Hindu