Pulse variational quantum eigensolver on cross-resonance based hardware

Understand

State-of-the-art noisy digital quantum computers can only execute short-depth quantum circuits.

• Variational algorithms are a promising route to unlock the potential of noisy quantum computers since the depth of the corresponding circuits can be kept well below hardware-imposed limits.
• Typically, the variational parameters correspond to virtual $R_Z$ gate angles, implemented by phase changes of calibrated pulses.
• By encoding the variational parameters directly as hardware pulse amplitudes and durations we succeed in further shortening the pulse schedule and overall circuit duration.