Qubit Routing using Graph Neural Network aided Monte Carlo Tree Search

Quantum Chemistry Calculations using Energy Derivatives on Quantum Computers

“…These contributions have been significant in their own respect despite them not being able to provide any advantage over the classical computational chemistry methods, such as density functional theory (DFT) [9], coupled cluster (CC) theory [10], and quantum Monte-Carlo methods [11]. This lack of advantage is attributed to the fact that much of the work done in the field is still * utkarsh.azad@research.iiit.ac.in in the exploratory phase, and the computational power offered by NISQ devices is considerably restricted due to the limited number of good quality qubits, absence of error correction and limited qubit connectivity [12].…”

Nuwa: A Quantum Circuit Transpiler Based on a Finite-Horizon Heuristic for Placement and Routing

“…This optimization problem is often modelled as a placement and routing problem of finding a mapping of the abstract qubits to the physical qubits (placement), followed by iterations of performing entangling gates between qubits that are far apart by moving them closer to each other (routing), for example, via Swap gates. The placement and routing problem has been extensively studied in the context of NISQ algorithms [3,4,7,[10][11][12][13][14][15][16][17][18][19][20][21][22][23], as well as in the fault-tolerant compilation of quantum algorithms using concatenated error-correcting codes [24], lattice surgery-based fault-tolerant quantum computing (FTQC) [7,25], and defect-based FTQC [26].…”

“…Some of the solutions relevant to our approach are those based on the observation that the placement and routing problem is an inherently temporal problem over the span of multiple decision epochs. This includes an exact, but exponentially expensive, dynamic programming solution introduced in [13], temporal planning and constraint pro-gramming [16,19], and methods that use reinforcement learning [14,23]. On one hand, these approaches are superior to the greedy techniques that neglect the future impact of decisions made at earlier decision epochs.…”