New #openaccess publication #SciPost #Physics
A higher-order topological twist on cold-atom SO($5$) Dirac fields
Alejandro Bermudez, Daniel González-Cuadra, Simon Hands
SciPost Phys. 17, 003 (2024)
https://scipost.org/SciPostPhys.17.1.003
#UAM #IQOQI Innsbruck #ITP #LiverpoolUniversity
#AgenciaEstatalInvestigación
On Tuesday at #IQOQI Tobias Olsacher explained to me how to verify #HamiltonianSimulation. The paper https://arxiv.org/abs/2203.15846 is full of tricks and ideas, going towards a tutorial reviewing what you can do if you have access to decent measurements and enough coherence to make the characterization of a #QuantumDevice challenging.
The Hamiltonian learning involving an energy constraint is extremely #neat 💯 as an idea but apparently is sensitive to non-unitarity. A generalization is possible to do without an exact energy constraint and learn a parametrized Liouvillian but haih do we always need to need so many measurements? #quantum 🥲
The goal of digital quantum simulation is to approximate the dynamics of a given target Hamiltonian via a sequence of quantum gates, a procedure known as Trotterization. The quality of this approximation can be controlled by the so called Trotter step, that governs the number of required quantum gates per unit simulation time. The stroboscopic dynamics generated by Trotterization is effectively described by a time-independent Hamiltonian, referred to as the Floquet Hamiltonian. In this work, we propose Floquet Hamiltonian learning to reconstruct the experimentally realized Floquet Hamiltonian order-by-order in the Trotter step. This procedure is efficient, i.e., it requires a number of measurements that scales polynomially in the system size, and can be readily implemented in state-of-the-art experiments. With numerical examples, we propose several applications of our method in the context of verification of quantum devices: from the characterization of the distinct sources of errors in digital quantum simulators to determining the optimal operating regime of the device. We show that our protocol provides the basis for feedback-loop design and calibration of new types of quantum gates. Furthermore it can be extended to the case of non-unitary dynamics and used to learn Floquet Liouvillians, thereby offering a way of characterizing the dissipative processes present in NISQ quantum devices.
New #openaccess publication #SciPost #physics
Equal-time approach to real-time dynamics of quantum fields
Robert Ott, Torsten V. Zache, Jürgen Berges
SciPost Phys. 14, 011 (2023)
https://scipost.org/SciPostPhys.14.2.011
@dfg_public #HeidelbergUniversity #IQOQI #InnsbruckUniversity #SimonsFoundation
SciPost Physics
Quantum Observer
Marek Gluza