IBM Quantum Platform (previously known as IBM Quantum Experience) is an online platform that allows public and premium access to cloud-based quantum computing services provided by IBM. It includes access to IBM’s prototype quantum processors, tutorials on quantum computation, and an interactive textbook. As of February 2021, there are over 20 devices on the service, six of which are freely available to the public. The service can be used to run algorithms and experiments and to explore tutorials and simulations demonstrating possibilities with quantum computing.

IBM’s quantum processors use superconducting transmon qubits housed in dilution refrigerators at IBM Research’s Thomas J. Watson Research Center. Users interact with a quantum processor through the quantum circuit model of computation. Circuits can be created either graphically with the Quantum Composer or programmatically within the Jupyter notebooks of the Quantum Lab. Circuits are developed using Qiskit and can be compiled to OpenQASM for execution on real quantum systems.

The service was launched in May 2016 as the IBM Quantum Experience with a five-qubit processor and a matching simulator connected in a star-shaped pattern. At that time, users could only interact with the hardware through the Quantum Composer GUI, and quantum circuits were limited to the specific two-qubit gates available on the hardware. In July 2016, IBM launched the IBM Quantum Experience community forum, which was subsequently replaced by a Slack workspace. In January 2017, IBM expanded the IBM Quantum Experience by increasing the set of two-qubit interactions available on the five-qubit processor, extending the simulator to support custom topologies up to twenty qubits, and allowing users to interact with the device and simulator using quantum assembly (QASM) code. In March 2017, IBM released Qiskit to enable users to write code and run experiments on the processor and simulator more easily; a beginner's user guide was also added. In May 2017, IBM made a 16-qubit processor available on the IBM Quantum service. In January 2018, IBM launched a quantum awards program hosted on the IBM Quantum Experience. In May 2019, the service was overhauled, adding web-hosted Jupyter notebooks and integrating the online interactive Qiskit Textbook. After a redesign in March 2021, IBM made a greater distinction between the Composer GUI and the Jupyter notebooks, retiring the IBM Quantum Experience name in favor of the separate names IBM Quantum Composer and IBM Quantum Lab; the offering is now collectively called the IBM Quantum Platform. The IBM Quantum Composer is a graphical user interface (GUI) that allows users to construct quantum algorithms and run experiments. Users can run their quantum algorithms on a real quantum processor or use a simulator to see the results. Algorithms developed in the Quantum Composer are referred to as a "quantum score", because the composer resembles a musical score. The composer can also be used in scripting mode, where the user writes programs in the OpenQASM language.

Below is an example of a very small program built for IBM's 5-qubit computer. The program prepares a 3-qubit GHZ state — a three-qubit analogue of the Bell state — and then measures the qubits. The measurement collapses the GHZ state to one of two outcomes: |000> or |111>.

include "qelib1.inc"
qreg q[5];        // allocate 5 qubits (initialized to |00000>)
creg c[5];        // allocate 5 classical bits
h q[0];           // Hadamard on qubit 0
cx q[0], q[1];    // CNOT with control q0 and target q1; creates a Bell state between q0 and q1
                  // (|00> + |11>)/sqrt(2) on qubits 0 and 1
cx q[1], q[2];    // expand entanglement to qubit 2, producing a 3-qubit GHZ state
measure q[0] -> c[0];   // measuring q0 collapses the entire 3-qubit state
measure q[1] -> c[1];   // q1 and q2 will read the same value as q0
measure q[2] -> c[2];

Every instruction in the OpenQASM language is either the application of a quantum gate, initialization of the chip's registers to zero, or the measurement of those registers. In 2018, IBM reported that there were over 80,000 users of the IBM Quantum Experience, who collectively ran more than 3 million experiments. Many academic papers have been published by researchers who used the service, and university professors have incorporated IBM Quantum examples and experiments into their curricula. Dr. Christine Corbett Moran, a postdoctoral fellow at the California Institute of Technology, used the service while conducting research in Antarctica; Tara Tosic, a physics student at the École Polytechnique Fédérale de Lausanne (EPFL), used it while researching in the Arctic. People have also used IBM Quantum for various non-academic purposes, including the development of games such as "quantum battleships." External links: IBM Quantum Platform; IBM Quantum Experience; quantum computing; quantum programming.