The power of the quantum computer, meanwhile, lies in its much richer repertoire of states. A quantum computer also has bits — but instead of 0 and 1, its quantum bits, or qubits, can represent a 0, 1, or linear combination of both, which is a property known as superposition. This on its own is no special thing, since a computer whose bits can be intermediate between 0 and 1 is just an analog computer, scarcely more powerful than an ordinary digital computer. However, a quantum computer takes advantage of a special kind of superposition that allows for exponentially many logical states at once, all the states from to . This is a powerful feat, and no classical computer can achieve it.
The vast majority of quantum superpositions, and the ones most useful for quantum computation, are entangled. Entangled states are states of the whole computer that do not correspond to any assignment of digital or analog states of the individual qubits. A quantum computer is therefore significantly more powerful than any one classical computer — whether it be deterministic, probabilistic, or analog.
While today’s quantum processors are modest in size, their complexity grows continuously. We believe this is the right time to build and engage a community of new quantum learners, spark further interest in those who are curious, and foster a quantum intuition in the greater community. By making quantum concepts more widely understood — even on a general level — we can more deeply explore all the possibilities quantum computing offers, and more rapidly bring its exciting power to a world whose perspective is limited by classical physics.
With this in mind, we created the IBM Quantum Composer to provide the hands-on opportunity to experiment with operations on a real quantum computing processor. This field guide contains a series of topics to accompany your journey as you create your own experiments, run them in simulation, and execute them on real quantum processors available via IBM Cloud®.
If quantum physics sounds challenging to you, you are not alone. But if you think the difficulty lies in “hard math”, think again. Quantum concepts can, for the most part, be described by undergraduate-level linear algebra, so if you have ever taken a linear algebra course, the math will seem familiar.
The true challenge of quantum physics is internalizing ideas that are counterintuitive to our day-to-day experiences in the physical world, which of course are constrained by classical physics. To comprehend the quantum world, you must build a new intuition for a set of simple but very different (and often surprising) laws.
