The capacity to build and operate quantum computers, hardware platforms, error correction, and the algorithms and software that will extract advantage from them.
The Capability Development Index tracks the events that move a capability — operational use, technical breakthroughs, procurement decisions and the industrial base behind them — and places each on the record with the date it happened.
Recent developments cover the current period. Historical developments are the inflection points that produced Quantum Computing as it stands today.
The equation, developed alongside Werner Heisenberg's competing matrix formulation, gave quantum theory its mature mathematical form, laying the physical groundwork more than six decades before anyone proposed computing with it directly.
Benioff used quantum theory to describe a simplified computer, providing the first formal model of quantum computation. This helped bring the previously separate communities of quantum mechanics and computer science together.
Faced with exponential overhead when simulating quantum dynamics on digital computers, Richard Feynman argued in a widely cited talk that classical computers would always struggle to simulate quantum mechanical systems and suggested building computers that exploited quantum mechanics directly; Yuri Manin independently proposed that hardware based on quantum phenomena would be more efficient. The conjecture became the founding motivation for building quantum computers and is now credited as the field's conceptual starting point.
Their paper demonstrated that quantum mechanical effects could be harnessed for information security protocols. It opened quantum information science as a practical field adjacent to quantum computation.
The Oxford physicist described a quantum Turing machine capable of simulating any physical process, providing the theoretical foundation on which later quantum algorithms and complexity results were built.
The algorithm did not solve a practical problem but showed mathematically that querying a black box with a superposed quantum state yields more information than classical querying. It was the first in a family of oracle algorithms demonstrating quantum parallelism.
Another oracle algorithm establishing formal separation between quantum and classical query complexity. It extended the theoretical case that quantum computers could extract information faster than classical machines.
Peter Shor showed that a sufficiently large quantum computer could factor large numbers and compute discrete logarithms in polynomial time, breaking RSA and Diffie–Hellman key exchange, the foundations of widely used public-key cryptography. The result gave quantum computing its first killer application, a problem of genuine practical importance solvable dramatically faster than by any known classical method, drawing broad government and commercial attention and turning an academic curiosity into a strategic technology.
The algorithm demonstrated exponential quantum speedup for a structured oracle problem. It directly influenced the development of Shor's factoring algorithm the same year.
Unruh questioned whether decoherence would ever permit useful quantum computation. His scepticism framed the error-correction agenda that followed.
Working at Bell Labs, Lov Grover showed that a quantum computer could search an unsorted list faster than any classical method, a quadratic speedup that implies symmetric key lengths are effectively halved against quantum attack. It became, alongside Shor's algorithm, one of the two canonical results most often cited to justify building quantum computers at all.
Lloyd's proof validated Feynman's earlier conjecture that quantum hardware is suited to simulating quantum physics. It established quantum simulation as a rigorous application area.
The first small-scale working device established the technical feasibility of quantum computation using trapped ions and superconductors. Subsequent experiments increased qubit counts and reduced error rates.
The Japanese research group showed coherent quantum behaviour in a tiny superconducting circuit, establishing the qubit platform that Google, IBM and China's leading processors all rely on today.
The demonstration ran a small instance of Shor's algorithm on a nuclear magnetic resonance quantum computer, the first physical execution of an algorithm that had until then existed only on paper.
The Canadian company's quantum annealer, bought by Lockheed Martin, used a different computing approach to the general-purpose machines pursued by most rivals, and its claims of quantum speed-up were contested for years before wider acceptance that some quantum effects were genuinely at work.
The system marked the packaging of superconducting quantum processors into an integrated commercial product. It signalled the shift from laboratory apparatus to deployable quantum computing platforms.
Google reported a calculation performed millions of times faster than the Summit supercomputer, estimated to take classical machines 10,000 years. IBM disputed the claim, arguing the task could be done in about 2.5 days with optimised algorithms, sparking debate over the supremacy threshold.
The study identified ionising radiation as a source of correlated errors in superconducting qubits. It highlighted an environmental constraint on scaling fault-tolerant hardware.
The Chinese group claimed a classical computer would need 600 million years to generate the samples their processor produced in 20 seconds. It established a second national platform claiming quantum advantage, on photonics rather than superconductors.
The alloy could substitute for helium-3 in cooling quantum computing hardware. The announcement followed DARPA's call for the same capability, indicating parallel national efforts on cryogenic materials.
The solicitation targeted a critical supply-chain constraint on scaling quantum hardware, since helium-3 is scarce. It shows cryogenic infrastructure as a bottleneck capability.
Abu Dhabi's applied research institute continued work across multiple qubit approaches as part of a wider Gulf push to build domestic quantum computing expertise rather than rely solely on hardware and software developed in the United States, Europe or China.
Global government funding aimed at longer coherence times and lower error rates reached ten billion dollars. The scale of state backing reflected quantum computing's treatment as a strategic national capability.
The eight-qubit prototype was presented as evidence of a new, more error-resistant type of qubit built from exotic quasiparticles, though independent physicists urged caution given the field's history of retracted claims about the same underlying physics.
A thin layer of molybdenum diselenide integrated on nanostructured silicon coupled electronic and photonic degrees of freedom using structured twisted light. Operation at ambient conditions suggests a path away from cryogenic hardware.
Quantum algorithms were distributed across a photonic network link between trapped-ion modules, and two-qubit gates were teleported between remote nitrogen-vacancy centre registers in diamond. These results pointed towards modular, distributed quantum architectures as a scaling route.
New systems went to government and research partners beyond Europe, extending a company founded by, among others, a Nobel laureate in physics into a genuinely international customer base spanning several continents.
The Canadian nonprofit's yearly survey of specialists continued to inform how governments and companies plan migration away from vulnerable cryptography, with estimates for a cryptographically relevant quantum computer still spread across a wide range of years.
Companies including Quantum Machines, which makes control hardware for quantum processors, and Classiq, a quantum software firm, expanded internationally, part of a domestic industry that has grown around the country's national quantum initiative and its research universities.
The plan relies on new error-correcting codes intended to cut the number of physical qubits needed per logical qubit, with a large-scale machine targeted for the end of the decade at a new facility in the United States.
Hub institutions working across superconducting, photonic and trapped-ion platforms continued government-funded development toward the mission's staged qubit targets, part of an eight-year programme intended to give India an indigenous quantum computing capability rather than dependence on imported systems.
The 105-qubit superconducting processor showed logical error rates falling as more physical qubits were added to each logical qubit, a long-sought threshold, and ran a benchmark calculation Google said no classical supercomputer could complete in a feasible time.
Exact amplitudes for experimentally generated bitstrings were computed using a multiple-amplitude tensor network contraction algorithm. The work demonstrated a leap in classical simulation capability, tightening the bar for quantum advantage claims.
The approaches marked a critical step towards scaling beyond the noisy intermediate-scale quantum era into reliable architectures. Large-scale physical implementation nonetheless remained an engineering challenge.
The University of Science and Technology of China's 105-qubit superconducting chip ran a random circuit sampling benchmark that Chinese researchers said was many orders of magnitude harder to simulate classically than earlier such results, extending China's quantum hardware programme.
Site work and component development proceeded under a joint commitment from the Australian federal government and the Queensland state government, one of the largest public investments anywhere in a single quantum computing project.
IBM claimed better results than a conventional supercomputer for a physics simulation task. The result was presented as evidence of practical utility, though classical machines still outperformed quantum ones across real-world applications as of 2023.
A restricted Boltzmann machine implemented on a commercial annealing device generated novel small molecules with drug-like physicochemical properties. It was an early applied demonstration in drug discovery.