[Hybrid RBRC seminar] Scattering from energy levels: Truncated Spectrum Approach and Lüscher's method for the $\phi^4$ 1+1 theory

by Marton Lajer (Brookhaven)

Thursday 2 Mar 2023, 12:30 → 13:30 US/Eastern

2-160 (https://bnl.zoomgov.com/j/1606067399?pwd=am02b0xIUXZ6TDR3d1dWL05TTDdaUT09)

While the state of art of quantum computing is rapidly developing, it is important to look for interesting model systems in high energy physics where quantum supremacy could be reached on a noisy intermediate-scale quantum (NISQ) architecture. The 1+1 dimensional $\phi^4$ model is an ideal benchmark, as its $\mathbb{Z}_2$-preserving phase is particularly transparent with only one excitation, while the broken phase features a rich nonperturbative structure including bound states and kinks, and even open problems of separate interest (e.g. kink-antikink scattering amplitudes.)
 
I intend to give a didactic introduction to Lüscher's method for computing S-matrix elements. The method will be demonstrated using the Truncated Spectrum approach, a classical momentum-space algorithm well suited to bosonic QFTs in low dimensions. The focus will be on elastic scattering amplitudes and, by extension, (partially inclusive) inelastic transition rates. I will argue that plenty of interesting scattering information can be obtained from a NISQ quantum simulation without having to prepare wavepacket initial states.

video1764722203.mp4