Orchestrated Trios: Compiling for Efficient Communication in Quantum
  Programs with 3-Qubit Gates
Current quantum computers are especially error prone and require high levels
of optimization to reduce operation counts and maximize the probability the
compiled program will succeed. These computers only support operations
decomposed into one- and two-qubit gates and only two-qubit gates between
physically connected pairs of qubits. Typical compilers first decompose
operations, then route data to connected qubits. We propose a new compiler
structure, Orchestrated Trios, that first decomposes to the three-qubit
Toffoli, routes the inputs of the higher-level Toffoli operations to groups of
nearby qubits, then finishes decomposition to hardware-supported gates.
  This significantly reduces communication overhead by giving the routing pass
access to the higher-level structure of the circuit instead of discarding it. A
second benefit is the ability to now select an architecture-tuned Toffoli
decomposition such as the 8-CNOT Toffoli for the specific hardware qubits now
known after the routing pass. We perform real experiments on IBM Johannesburg
showing an average 35% decrease in two-qubit gate count and 23% increase in
success rate of a single Toffoli over Qiskit. We additionally compile many
near-term benchmark algorithms showing an average 344% increase in (or 4.44x)
simulated success rate on the Johannesburg architecture and compare with other
architecture types.
Casey Duckering Jonathan M. Baker Andrew Litteken Frederic T. Chong