Finding Traps in Non-linear Spin Arrays

Abstract

Precise knowledge of the Hamiltonian of a system is a key to many of its applications. Tasks such state transfer or quantum computation have been well studied with a linear chain, but hardly with systems, which do not possess a linear structure. While this difference does not disturb the end-to-end dynamics of a single excitation, the evolution is significantly changed in other subspaces. Here we quantify the difference between a linear chain and a pseudo-chain, which have more than one spin at some site (block). We show how to estimate a number of all spins in the system and the intra-block coupling constants. We also suggest how it is possible to eliminate excitations trapped in such blocks, which may disturb the state transfer. Importantly, one uses only at-ends data and needs to be able to put the system to either the maximally magnetized or the maximally mixed state. This can obtained by controlling a global decoherence parameter, such as temperature.

5 pages, 1 figure

References in corpus (9)

• Perfect Transfer of Arbitrary States in Quantum Spin Networks
• Full control by locally induced relaxation
• Perfect state transfer on a spin-chain without state initialization
• Electron wavepacket propagation and entanglement in a chain of coupled quantum dots
• Coupling strength estimation for spin chains despite restricted access
• Hamiltonian tomography in an access-limited setting without state initialization
• Indirect Hamiltonian Identification through a small gateway
• Optimal quantum chain communication by end gates
• Computation on Spin Chains with Limited Access

Cited by in corpus (6)

• Indirect Quantum Tomography of Quadratic Hamiltonians
• Spin chains for robust state transfer: Modified boundary couplings vs. completely engineered chains
• Quantum metrology with non-equilibrium steady states of quantum spin chains
• Estimation of Coupling Constants of a Three-Spin Chain: Case Study of Hamiltonian Tomography with NMR
• Robustly learning the Hamiltonian dynamics of a superconducting quantum processor
• Bypassing state initialization in Hamiltonian tomography on spin-chains