Where We Are: The NISQ Era
Current quantum computers are described as Noisy Intermediate-Scale Quantum (NISQ) devices: machines with between 50 and a few thousand qubits that are too noisy and error-prone for full fault-tolerant operation, but large enough to run useful experiments and early applications.
In 2019, Google announced that its Sycamore processor had completed a specific calculation in 200 seconds that Google estimated would take the world's most powerful classical supercomputer 10,000 years. IBM disputed the classical timeline but acknowledged the milestone's significance. In 2023, IBM unveiled its 1,121-qubit Condor processor, the largest superconducting quantum processor ever built at that time.
These are real achievements. But it is important to understand that quantum supremacy demonstrations are performed on contrived problems specifically designed to be hard for classical computers. No NISQ device has yet demonstrated a practical advantage over the best classical algorithms on a real-world commercially relevant problem. That milestone, called quantum advantage, remains the field's most important near-term goal.
The path to fault-tolerant quantum computing spans years of careful, incremental engineering progress | Photo: Unsplash
Global Investment Race
Governments and corporations worldwide have recognised quantum computing as a strategically critical technology. The United States has committed over $1.8 billion through the National Quantum Initiative. The European Union is investing 1 billion euros through the Quantum Flagship programme. China has reportedly invested more than $15 billion in quantum research.
The private sector has followed with enormous speed. IBM, Google, Microsoft, Amazon, and Honeywell are all investing heavily in quantum hardware and cloud services. Venture capital funding for quantum startups exceeded $2.35 billion globally in 2022 alone. Over 300 quantum computing startups now operate worldwide, targeting applications from chemistry to finance.
The Quantum Internet
Researchers are working toward a quantum internet, a communication network that uses quantum entanglement and quantum key distribution to transmit information with theoretically perfect security. Unlike classical encryption which could be broken by a sufficiently powerful computer, the security of quantum communication is guaranteed by the laws of physics. Any attempt to intercept a quantum communication disturbs the quantum state and immediately alerts the communicating parties.
China launched the world's first quantum satellite in 2016 and has demonstrated quantum key distribution over distances of more than 1,000 kilometres. The Netherlands, the United States, and several other countries are building metropolitan quantum networks with the aim of eventually connecting them into a global quantum internet that secures communications permanently.
The Remaining Challenges
- Error Correction at Scale — Building a fault-tolerant quantum computer requires encoding each logical qubit across many physical qubits. Current estimates suggest 1,000 physical qubits are needed per error-corrected logical qubit. Getting to one million high-quality physical qubits is a monumental engineering challenge that will take many years to resolve
- Qubit Quality — It is not enough to add more qubits. The quality of each qubit, measured by coherence time and gate fidelity, must also improve substantially. Current two-qubit gate error rates of 0.1 to 1% are too high for deep fault-tolerant circuits and need to fall by an order of magnitude or more
- Cryogenic Engineering — Most quantum processors must operate near absolute zero inside large cryogenic systems. Scaling these systems to house millions of qubits while maintaining necessary cooling and electromagnetic isolation is a serious materials and engineering challenge at the frontier of what is physically achievable
- Algorithm Development — Even if perfect hardware existed today, quantum algorithms that deliver clear advantage over classical algorithms for commercially valuable problems are still being developed. Translating theoretical speedups to practical real-world problems requires significant ongoing research effort from the quantum computing community
- Workforce Gap — Quantum computing requires expertise spanning quantum physics, computer science, electrical engineering, and materials science simultaneously. The global supply of people with this combination of skills is extremely limited, and educational pipelines have only recently begun addressing this critical shortage
McKinsey Global Institute, 2023
McKinsey estimates that quantum computing could generate between $450 billion and $850 billion in value across pharmaceutical, chemical, financial, and automotive sectors by 2035. Organisations that begin building quantum expertise and hybrid classical-quantum workflows today will be significantly better positioned when the technology matures than those who wait until fault-tolerant machines arrive.