Great question. Both the IBM Q experience and Rigetti Forest allow users to write quantum algorithms with Python that can execute on real quantum hardware. Forest is different in 3 main ways:
1. Forest was designed with near-term applications in mind. Specifically, it uses our quantum instruction set (Quil) [1], which was designed for implementing classical/quantum hybrid algorithms [2]. These algorithms can leverage near-term quantum devices significantly more than "textbook" quantum algorithms (like Shor's). IBM Q places much less emphasis on hybrid computation.
2. Forest provides raw access to the quantum hardware. There's an API [3] for users to run "analog" experiments to understand the performance and noise characteristics of our qubits. If you're developing near-term applications for quantum computers, having access to this physical layer of quantum devices is crucial. IBM Q doesn't provide a similar API to my knowledge.
3. Programs written with Forest can execute on up to 30 virtual qubits on the Rigetti QVM [4]. This allows users to develop quantum algorithms ahead of any physical device that can run them. Especially if you include noise modeling (we do), 30 qubits is well beyond what you could simulate with your laptop. IBM Q offers a 20 qubit simulator, which is roughly 1000 times less powerful than 30 qubits.
I must mention that IBM recently announced their experience will have up to 17 real qubits! This is larger than any physical device Forest is currently connected to, and represents exciting progress.
Can you measure and reinitialize qubits? Testing fault-tolerant error correction with eight qubits would be very exciting.
Is there a chance that you can roughly summarize noise levels, to give an idea of what to expect? Something along the lines of Table 2 (page 6) in arXiv:1705.02771 would be helpful.
A. Bermudez et al. "Assessing the progress of trapped-ion processors towards fault-tolerant quantum computation", arXiv:1705.02771 https://arxiv.org/abs/1705.02771
The computing model is given by Quil [0]. Section III-F talks about exactly this idea of "measurement-for-effect". You can use measurement in Quil as a way to project into a state that you want. (You can even use a conditional instruction to get feedback and flip it with an X if it measures into an undesired state.)
Awesome, thanks for the reply. Would you be providing the computational resources to run those 30 qubit simulated experiments? Would there be a limit? That's no small system size!
