Having a quantum computer up and running requires a considerable investment in classical computing resources, given the number of measurements and control operations that need to be executed and interpreted to do so. At IBM they can do this by having the necessary software to control and interpret the flow of information that arises from the quantum side. It is about Little bitand open source system thatat its most basic level according to Ars Technica, can be considered equivalent to a compiler, and that IBM has decided to open to third parties.
Qiskit’s mission at a basic level is to take the algorithms defined by the humans working with the system and convert them to elements that the quantum system hardware can execute. It must be taken into account that in a quantum computer, at least for now, everything that happens in its processor happens under the control of external hardware, which generally act by generating a series of laser or microwave pulses.
Therefore, what Qiskit, or equivalent third-party software such as Microsoft’s Q#, does is convert the code it receives into commands that are sent to hardware external to the processor. They also keep track of where in the processor things are happening. Quantum computers work by performing specific operations, known as gates, on qubits, either in parts or individually.
In order to do so, they have the necessary information about which qubit whoever is using the quantum system is targeting. Furthermore, in the case of elements such as superconducting qubits, where there may be changes from one device to another, and the hardware qubits that end up being used can have a notable effect on the results of the calculations.
That’s why most tools like Qiskit offer the option to work directly with the hardware. But if a developer decides not to, the software can transform generic instructions, as we have seen, into a series of actions that will execute any algorithm coded for use with it. This implies that the software is responsible for choosing which physical qubits it uses, which gates it uses, and which measurements it executes and in what order. For this reason, many decide to use Qiskit with IBM quantum computers.
These types of tools will take on a more prominent role in the coming years, and there are already organizations experimenting with qubit hardware design that can warn when there is a common type of error. There are also advances in the development of logical qubits that enable error correction. It is also likely that companies that provide access to quantum computers will want to modify their software to have these and other functions activated by default, without the algorithm designers having to make changes.
IBM therefore decided to rewrite Qiskit in Rust (it was originally written in Python), which improved its overall performance, leading the company to develop a cross-platform test suite. This suite is responsible for generating quantum circuits from abstract representations of algorithms, and for manipulating and optimizing the resulting circuit.
Despite this, due to all the variables involved in the use of software in quantum computing, and the difference between results from one tool to another, IBM has decided to open its system so that those who use its quantum systems can use its tools and do not depend completely of yours.
Currently Support now exists for six third-party Qiskit features which are divided into two categories: those of the first can be used as independent applications, and are focused on offering solutions to problems for users who do not have experience in programming quantum computers. These are in charge of calculating the base state in terms of energy of the molecules, while those in the second category are in charge of executing optimizations.
