Noisy intermediate-scale quantum (NISQ)

Definition

Noisy intermediate-scale quantum (NISQ) refers to a class of quantum computers that have a limited number of qubits, typically between 50 to a few hundred, and are subject to significant errors and noise during computations. These devices are not yet capable of performing fault-tolerant quantum computation but can be utilized for practical applications in quantum machine learning, quantum chemistry, and optimization problems, serving as a bridge between classical and fully error-corrected quantum systems.

5 Must Know Facts For Your Next Test

1. NISQ devices are characterized by their limited number of qubits and high levels of operational noise, which restrict their computational capabilities.
2. They can still be used for practical experiments and applications in quantum chemistry, such as simulating molecular structures and interactions.
3. Despite their imperfections, NISQ computers can leverage techniques like variational algorithms to perform useful computations that may not be achievable on classical computers.
4. NISQ technology represents an important transitional phase towards the development of more advanced quantum computing systems that can achieve fault tolerance.
5. Research in NISQ computing is actively exploring how to optimize algorithms to make the most of current hardware limitations while also improving error rates.

Review Questions

• How do NISQ devices differ from fully fault-tolerant quantum computers?
  • NISQ devices differ from fully fault-tolerant quantum computers primarily in their ability to manage errors during computations. While NISQ computers operate with a limited number of qubits and are subject to significant noise, fault-tolerant computers are designed to correct these errors, allowing them to perform more complex calculations reliably. This difference affects how each type of device can be utilized for practical applications, with NISQ being more suited for experimental setups while the latter aims for reliable long-term computations.
• Discuss the potential applications of NISQ technology in the field of quantum chemistry.
  • NISQ technology holds significant potential in quantum chemistry by enabling simulations of molecular systems and chemical reactions that are difficult or impossible for classical computers to model accurately. With their ability to represent complex quantum states, NISQ devices can help chemists better understand molecular properties and interactions. Variational algorithms implemented on NISQ devices allow researchers to optimize molecular parameters and explore energy landscapes more effectively, leading to advancements in material science and drug discovery.
• Evaluate the implications of using NISQ devices for research in quantum machine learning compared to classical approaches.
  • Using NISQ devices for research in quantum machine learning presents unique implications compared to classical approaches. The integration of quantum principles can potentially lead to enhanced performance in tasks such as data classification and clustering due to the superposition and entanglement properties inherent in qubits. However, challenges remain due to the noise and errors present in NISQ systems, which may limit their effectiveness. Researchers must therefore develop novel algorithms that are specifically designed for these noisy environments, paving the way for future improvements and establishing a new paradigm that combines classical and quantum methodologies.

Related terms

Quantum Supremacy: The point at which a quantum computer can perform a calculation that is infeasible for any classical computer to complete in a reasonable time frame.

Quantum Circuit: A model for quantum computation in which a sequence of quantum gates is applied to a set of qubits, representing the computational process.

Quantum Error Correction: A set of techniques used in quantum computing to protect quantum information from errors due to decoherence and other noise.