The roadmap: fault-tolerant quantum computers and your next step

Where are quantum computers heading in the coming years, and how can someone who has finished this school carry on? See company roadmaps, career paths and resources to keep learning.

Three eras

Today we are in the era of noisy intermediate-scale (NISQ) devices: there are hundreds of qubits, but errors block long algorithms. The next step is the first small fault-tolerant computers: tens or hundreds of logical qubits and millions of error-free gates. The most distant goal is machines with thousands of logical qubits that can run Shor’s algorithm on large numbers.

IBM has announced that it aims to build a fault-tolerant computer called Starling, with 200 logical qubits able to run 100 million gates, by 2029. Google, Quantinuum, QuEra and others have published similar roadmaps. These dates are goals, not promises; but progress has clearly accelerated in recent years.

The first useful applications

Most experts expect the first useful applications to come in chemistry and materials science, that is in simulating quantum systems: better batteries, catalysts and drug molecules. The advantage in optimisation and machine learning is less clear. In cryptography preparation has already begun: the move to post-quantum encryption.

Your next step

In this school you have seen the basic map of quantum computing, from qubits to error correction. To carry on, the free courses on IBM Quantum Learning, the Qiskit documentation and the Qiskit Global Summer School held every summer are good starting points. If you want to go deeper into the maths, Nielsen and Chuang’s “Quantum Computation and Quantum Information” is the classic textbook of the field.

Quantum software engineering, algorithm research, quantum hardware engineering and post-quantum security are newly emerging career paths. Communities such as QWorld and its local branches run workshops around the world. Still, the best way to learn is to build your own small project: download one of the packages on this site, run it and change it.

Try it yourself

The Grover search you saw at the start of the school finds the right one of four boxes in a single step. On today’s computers this circuit is limited to a few qubits; on fault-tolerant computers the same idea will work over millions of options. Remove the oracle and see once more how the result goes back to 25%.

Open the circuit in your browser

The circuit playground is in Turkish. Button guide: “1000 kez ölç” = measure 1000 times, “Durum vektörünü göster” = show the state vector, “Bu devrenin Qiskit kodu” = this circuit’s Qiskit code, “Geri al” = undo, “Temizle” = clear. Click a gate in the circuit to remove it.

Key points

We are in the NISQ era today; the next goal is fault-tolerant computers with logical qubits.
IBM aims for Starling with 200 logical qubits by 2029; other companies have roadmaps too.
The first useful applications are expected in chemistry and materials simulation.
IBM Quantum Learning, the Qiskit documentation, Nielsen and Chuang and your own projects are good ways to carry on.

Test yourself

According to experts, in which field are the first useful quantum applications most likely to come?

Video games
Chemistry and materials simulation
Word processors

Show the answer

Chemistry and materials simulation. Simulating quantum systems is where quantum computers are naturally strongest.

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