RRI Scientists Develop New Approach to Control Quantum Decoherence

Context:

Recently, Scientists at the Quantum Information and Computing (QuIC) laboratory of Raman Research Institute (RRI), Bengaluru, have demonstrated a novel technique to improve the stability of quantum states used in quantum computing. The research, published in Physical Review A of the American Physical Society, focuses on controlling decoherence and preventing entanglement sudden death through Single-Shot Operation.

What is Quantum Computing?

Traditional computers use bits, represented as 0 or 1. Quantum computers use quantum bits or qubits, which exploit principles of quantum mechanics to process information in fundamentally different ways.

• • Superposition: Superposition allows a qubit to exist in a combination of 0 and 1 simultaneously. This enables quantum systems to process information in ways that are not possible for conventional computers.
  • Quantum Entanglement: Entanglement is a phenomenon in which two quantum particles become strongly correlated. The state of one particle is linked to the state of another, making entanglement an important resource for quantum information processing.

What is Quantum Decoherence?

• • • Quantum states are extremely fragile and can be disturbed by thermal vibrations, electromagnetic fields, radiation and other environmental interactions. The resulting loss of quantum coherence is called decoherence.
    • Another related phenomenon is “entanglement sudden death”, where entanglement disappears abruptly. Decoherence and entanglement loss can introduce errors and undermine the reliability of quantum computations.

About RRI's New Approach:

• • • Traditionally, scientists use repeated corrective interventions and quantum error-correction techniques to delay decoherence. However, repeated operations require significant resources and may themselves introduce errors.
    • The RRI team demonstrated that a single, carefully timed operation can potentially delay decoherence and prevent entanglement sudden death. Thus, timing itself becomes a new control parameter.
    • The researchers emphasise that this is a proof of concept, not a complete solution to decoherence or a replacement for quantum error correction. Further testing on different quantum computing platforms is required.

Significance:

The approach could potentially:

• • • Reduce repeated corrective interventions.
    • Improve control over fragile quantum states.
    • Complement quantum error-correction methods.
    • Contribute to the development of more reliable and scalable quantum processors.

Applications of Quantum Computing:

Quantum computing has potential applications in:

• • • Cryptography: Quantum algorithms such as Shor's algorithm could threaten existing encryption systems.
    • Drug discovery: Simulation of molecules and chemical reactions.
    • Materials science: Development of advanced materials.
    • Optimisation: Logistics, supply chains and traffic management.
    • Scientific research: Modelling complex physical and chemical systems.

India and Quantum Technology:

The research is significant in the context of India's National Quantum Mission, launched to strengthen capabilities in quantum computing, communication, sensing, metrology, materials and devices.

Conclusion:

The RRI research represents an important advance in controlling fragile quantum states. By using the timing of a single operation as an additional control parameter, it could complement existing error-correction methods. However, wider testing across different quantum-computing platforms is necessary before practical applications can be established.