16 research outputs found
Robust Control of Single-Qubit Gates at the Quantum Speed Limit
Fastness and robustness are both critical in the implementation of
high-fidelity gates for quantum computation, but in practice, a trade-off has
to be made between them. In this paper, we investigate the underlying robust
time-optimal control problem so as to make the best balance. Based on the
Taylor expansion of the system's unitary propagator, we formulate the design
problem as the optimal control of an augmented finite-dimensional system at its
quantum speed limit (QSL), where the robustness is graded by the degree of
series truncation. The gradient-descent algorithm is then introduced to
sequentially seek QSLs corresponding to different orders of robustness.
Numerical simulations for single-qubit systems show that the obtained
time-optimal control pulses can effectively suppress gate errors (to the
prescribed robustness order) caused by qubit frequency and field amplitude
uncertainties. These results provide a practical guide for selecting pulse
lengths in the pulse-level compilation of quantum circuits
Mesoporous Polydopamine Loaded Pirfenidone Target to Fibroblast Activation Protein for Pulmonary Fibrosis Therapy
Recently, fibroblast activation protein (FAP), an overexpressed transmembrane protein of activated fibroblast in pulmonary fibrosis, has been considered as the new target for diagnosing and treating pulmonary fibrosis. In this work, mesoporous polydopamine (MPDA), which is facile prepared and easily modified, is developed as a carrier to load antifibrosis drug pirfenidone (PFD) and linking FAP inhibitor (FAPI) to realize lesion-targeted drug delivery for pulmonary fibrosis therapy. We have found that PFD@MPDA-FAPI is well biocompatible and with good properties of antifibrosis, when ICG labels MPDA-FAPI, the accumulation of the nanodrug at the fibrosis lung in vivo can be observed by NIR imaging, and the antifibrosis properties of PFD@MPDA-FAPI in vivo were also better than those of pure PFD and PFD@MPDA; therefore, the easily produced and biocompatible nanodrug PFD@MPDA-FAPI developed in this study is promising for further clinical translations in pulmonary fibrosis antifibrosis therapy
Experimental Realization of Two Qutrits Gate with Tunable Coupling in Superconducting Circuits
Gate-based quantum computation has been extensively investigated using
quantum circuits based on qubits. In many cases, such qubits are actually made
out of multilevel systems but with only two states being used for computational
purpose. While such a strategy has the advantage of being in line with the
common binary logic, it in some sense wastes the ready-for-use resources in the
large Hilbert space of these intrinsic multi-dimensional systems. Quantum
computation beyond qubits (e.g., using qutrits or qudits) has thus been
discussed and argued to be more efficient than its qubit counterpart in certain
scenarios. However, one of the essential elements for qutrit-based quantum
computation, two-qutrit quantum gate, remains a major challenge. In this work,
we propose and demonstrate a highly efficient and scalable two-qutrit quantum
gate in superconducting quantum circuits. Using a tunable coupler to control
the cross-Kerr coupling between two qutrits, our scheme realizes a two-qutrit
conditional phase gate with fidelity 89.3% by combining simple pulses applied
to the coupler with single-qutrit operations. We further use such a two-qutrit
gate to prepare an EPR state of two qutrits with a fidelity of 95.5%. Our
scheme takes advantage of a tunable qutrit-qutrit coupling with a large on/off
ratio. It therefore offers both high efficiency and low cross talk between
qutrits, thus being friendly for scaling up. Our work constitutes an important
step towards scalable qutrit-based quantum computation.Comment: 12 pages, 8 figure