Demonstration of universal control between non-interacting qubits using the Quantum Zeno effect

Abstract

The Zeno effect occurs in quantum systems when a very strong measurement is applied, which can alter the dynamics in non-trivial ways. Despite being dissipative, the dynamics stay coherent within any degenerate subspaces of the measurement. Here we show that such a measurement can turn a single-qubit operation into a two- or multi-qubit entangling gate, even in a non-interacting system. We demonstrate this gate between two effectively non-interacting transmon qubits. Our Zeno gate works by imparting a geometric phase on the system, conditioned on it lying within a particular non-local subspace. These results show how universality can be generated not only by coherent interactions as is typically employed in quantum information platforms, but also by Zeno measurements.

Dissipative preparation and stabilization of many-body quantum states in a superconducting qutrit array

“…For example, because of the large shifts of the cavity spectrum, quantum non-demolition measurement can be performed "selectively" between one state and its orthogonal subspace [47]. In the context of multiple qubits, this regime has been used to demonstrate a coherent entangling gate between non-interacting qubits [48,49]. In addition, the strong dispersive regime enables control and entanglement of quantum states encoded in cavity modes [50][51][52].…”

Multiprocessing Quantum Computing through Hyperfine Couplings in Endohedral Fullerene Derivatives

“…The function type is determined by observing the phase of the ESE signal. All four possible U f were performed by the combination of a geometric phase gate [15] and a NOT gate. Figure 3a and b shows one of the four U f gates, and the signals of this particular U f gate were shown in Figure 3c.…”

Quantum Zeno and Anti‐Zeno Effects in the Dynamics of Non‐Degenerate Hyper‐Raman Processes Coupled to Two Linear Waveguides

“…[38][39][40] Early experimental realizations of QZE have been followed by exciting recent experiments having much more controls and precision. [41] Experimental realization of QZE paved the way for various applications of QZE, [38,[42][43][44][45] ranging from the enhancement of the resolution of absorp- tion tomography [44,45] to the demonstration of an entangling gate between two effectively non-interacting transmon qubits, [46] the reduction of communication complexity [47] to the QZE and QAZE based noise spectroscopy [48] to the utilization of QZE to achieve improved precision of metrology in the presence of non-Markovian noise. [49] Interesting applications of QZE and QAZE are also found in opposing decoherence by restricting the dynamics of the system in a decoherence-free subspace, [50] quantum interrogation measurement, [38] counterfactual secure quantum communication, [43,51] isolating quantum dot from its surrounding electron reservoir, [52] protecting the entanglement between two interacting atoms.…”