Skip to content

Quantum Program Transpilation

Transpilation is the process of optimizing an already-synthesized quantum program and matching it to the desired hardware. It includes optimizations, such as combining a sequence of gates into an equivalent single gate, and transformations, such as qubit routing (i.e., applying swap gates in order to apply 2-qubit gates on partially connected hardware).

Classiq synthesis includes transpilation. However, the transformations applied to the quantum program affect the hierarchical nature of the quantum program. For example, the gates representing functions are decomposed to basis gates, and thus do not appear in the transpiled quantum program. To visualize the hierarchical quantum program in a meaningful way, the analyzer web application uses the non-transpiled quantum program. On the other hand, when executing a quantum program, it is preferable to use the transpiled quantum program, because it is already optimized for the given hardware. Thus, the Executor uses the transpiled quantum program.

The synthesis results include both quantum programs, in all output formats that you request. In addition, when using hardware-aware synthesis, the output also includes the quantum program in the format required for running on the provided hardware.

In certain cases, the Classiq executor re-transpiles quantum programs immediately before execution. This is to minimize execution errors and make sure that all executed gates are compatible with the requested hardware. See execution preferences.

Transpilation Options

  • none - no transpilation.
  • decompose - decompose all of the functions according to the basis gates of the backend. This is the default option.
  • light - a heavier transpilation method to better optimize the quantum programs. Best suited for fully connected hardwares.
  • medium - another heavy transpilation method, that optimizes the quantum program even further, but takes more time. This method is optimal for optimization of hardwares with more complex connectivity.
  • auto optimize - an option to let the Classiq platform to choose the transpilation automatically, based on the chosen backend.
  • intensive - designed for maximum optimization of quantum programs and is particularly well-suited for quantum hardware with complex connectivity.
  • custom - offers users a personalized approach to optimizing quantum circuits while considering various factors that contribute to the circuit's performance. It employs an internal decision-making process that takes into account specific optimization criteria, ensuring that quantum programs are transpiled in a way that maximizes efficiency and resource utilization for the chosen backend. This option's primary focus is on delivering the best possible circuit performance.


The heavier the transpilation method is, the quantum programs will be optimized better, but the transpilation process will take longer.