For this challenge, we are asked to find the name of a quantum computer.
The hint states that "This beast operates on 53 qubits and recently achieved 'Quantum Supremacy'. We are sure that you know its name."
Doing a quick google search on Quantum Supremacy and 53 qubits, we find a news article by SiliconANGLE from late 2019.
Link: https://siliconangle.com/2019/10/23/google-reaches-quantum-supremacy-milestone-53-qubit-sycamore-chip/
Result: Going through the page, we learn that at one of Google's research labs, they developed a 53-qubit, superconducting chip called Sycamore. Google claimed that Sycamore achieved quantum supremacy, "the ability to perform complex calculations too difficult for even the most sophisticated classical machines", by successfully completing complex calculations.
Flag: riftCTF{Sycamore} 