NISQ, which stands for Noisy Intermediate-Scale Quantum, refers to the current generation of quantum computers. These devices have several tens to a few hundred qubits and are characterized by their ability to perform quantum operations, but with significant noise and errors that limit their capabilities. The term was coined by John Preskill in 2018 to describe the near-term quantum computing landscape.
At Quandela, we’re pushing the boundaries of NISQ-era quantum computing with our photonic approach. Our technology offers unique advantages in mitigating noise and scaling up quantum systems, bringing us closer to practical quantum advantage.
Key Characteristics of NISQ Devices
- Qubit Count: Typically ranging from tens to a few hundred qubits
- Limited Coherence: Qubits maintain their quantum states for short periods
- Noisy Operations: Quantum gates and measurements are prone to errors
- Lack of Error Correction: Insufficient resources for full quantum error correction
- Hybrid Algorithms: Often used in conjunction with classical computers for practical applications
Potential of NISQ Era Computing
Typical and promising NISQ Era applications.
- Quantum Supremacy Demonstrations: Showing quantum advantages in specific, often contrived tasks
- Variational Algorithms: Implementing algorithms like VQE (Variational Quantum Eigensolver) for chemistry and materials science
- Quantum Machine Learning: Exploring quantum-enhanced machine learning techniques
- Optimization Problems: Tackling certain optimization tasks in fields like finance and logistics
- Quantum Simulation: Simulating quantum systems for scientific research
Limitations of NISQ Technology
- Error Accumulation: Errors build up quickly, limiting the depth of quantum circuits
- Limited Algorithmic Applications: Many proposed quantum algorithms require error-corrected qubits to operate at useful scale
- Variability: Results can be inconsistent due to noise and device instability
- Classical Competition: Improved classical algorithms sometimes outperform NISQ devices
- Scalability Challenges: Increasing qubit count while maintaining or improving qubit quality is difficult
Frequently Asked Questions About NISQ
- How does NISQ differ from fault-tolerant quantum computing? NISQ devices lack full error correction and have limited qubit counts, while fault-tolerant systems will have error correction and many more qubits.
- Can NISQ computers solve practical problems? NISQ devices show promise for certain specialized tasks, but their practical applications are still being explored and are limited by noise and errors.
- How long is the NISQ era expected to last? The duration is uncertain, but many experts expect the NISQ era to continue for several years as researchers work towards fault-tolerant quantum computers.
- Are all current quantum computers considered NISQ devices? Most current quantum computers are considered NISQ devices, regardless of their underlying technology (superconducting, ion trap, photonic, etc.).
- What comes after the NISQ era? The goal is to develop fault-tolerant quantum computers with error correction, enabling the full potential of quantum algorithms and applications.