An introduction to qubits
What are qubits and why are they important?
Simulations are extremely useful in the modern world, from supercomputers modelling the progression of weather systems to virtual reality headsets presenting users with accurate simulacra of different environments. A virtual (or simulated) qubit is no different.
It is simply a classical computer's representation of a qubit.
The development of quantum mechanics came long before the concepts of qubits and quantum computers were conceived. When this happened and it came to exploring what qubits could do, the initial ideas could be worked out using the equations of quantum mechanics that were - and are - extremely well-known to physicists.
The theory of quantum computers began in a very low-tech way, probably with just pen and paper. As interest in the topic grew in the academic community, simple computer programs were written to automate some of the mathematical calculations. Even though they weren't described as such, these were the first virtual or simulated qubits.
These programs have come a long way! The state-of-the-art programs have been optimised in a variety of ways. They can run on high performance supercomputing clusters. They can leave out the least important parts of the calculation in order to run faster.
When none of the noisy, unwanted interactions that cause real-life qubits to decohere are included in the programs, the virtual qubits are called perfect qubits. When these interactions are modelled, the resulting simulations can be used to assess their impact on real-life qubits. This informs the design and development of the entire quantum computing stack, aiming to make both the hardware and the algorithms more resilient to noise.
