We introduce methods for clock synchronization that make use of the adiabatic exchange of nondegenerate two-level quantum systems: ticking qubits. Schemes involving the exchange of $N$ independent qubits with frequency $\ensuremath{\omega}$ give a synchronization accuracy that scales as ${(\ensuremath{\omega}\sqrt{N})}^{\ensuremath{-}1}$---i.e., as the standard quantum limit. We introduce a protocol that makes use of ${N}_{c}$ coherent exchanges of a single qubit at frequency $\ensuremath{\omega}$, leading to an accuracy that scales as ${(\ensuremath{\omega}{N}_{c})}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}{N}_{c}$. This protocol beats the standard quantum limit without the use of entanglement, and we argue that this scaling is the fundamental limit for clock synchronization allowed by quantum mechanics. We analyze the performance of these protocols when used with a lossy channel.We introduce methods for clock synchronization that make use of the adiabatic exchange of nondegenerate two-level quantum systems: ticking qubits. Schemes involving the exchange of $N$ independent qubits with frequency $\ensuremath{\omega}$ give a synchronization accuracy that scales as ${(\ensuremath{\omega}\sqrt{N})}^{\ensuremath{-}1}$---i.e., as the standard quantum limit. We introduce a protocol that makes use of ${N}_{c}$ coherent exchanges of a single qubit at frequency $\ensuremath{\omega}$, leading to an accuracy that scales as ${(\ensuremath{\omega}{N}_{c})}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}{N}_{c}$. This protocol beats the standard quantum limit without the use of entanglement, and we argue that this scaling is the fundamental limit for clock synchronization allowed by quantum mechanics. We analyze the performance of these protocols when used with a lossy channel.

arXiv:quant-ph/0505112Physical Review AOct 3, 2005118 citations

Isotropic quantum beats

P. Johansson, I. E. Mazets, Oleg S. Vasyutinskii +1 more

The European Physical Journal DAug 30, 20040 citations

Effects of residual exchange coupling on simultaneously driven spin qubits

Heun Mo Yoo, Tanner M. Janda, Victor Yu +3 more

Exchange coupling and microwave drives are widely used control mechanisms for spin qubits. However, the influence of exchange coupling on microwave-driven spin dynamics is not fully understood. We report simultaneous drive measurements of two spin qubits as a function of exchange coupling and drive power. When the Rabi frequency exceeds exchange, we observe a beating pattern in the Rabi oscillations. In the opposite limit, two exchange-split patterns emerge in the Rabi chevrons. We find that these exchange-induced effects are suppressed when the difference in the Rabi frequencies exceeds the exchange coupling. A theoretical model is developed that reproduces the main features in our data.Exchange coupling and microwave drives are widely used control mechanisms for spin qubits. However, the influence of exchange coupling on microwave-driven spin dynamics is not fully understood. We report simultaneous drive measurements of two spin qubits as a function of exchange coupling and drive power. When the Rabi frequency exceeds exchange, we observe a beating pattern in the Rabi oscillations. In the opposite limit, two exchange-split patterns emerge in the Rabi chevrons. We find that these exchange-induced effects are suppressed when the difference in the Rabi frequencies exceeds the exchange coupling. A theoretical model is developed that reproduces the main features in our data.

cond-mat.mes-hallCross-listedarXiv:2609.15751Sep 15, 2026

Quantum beats in absorption

Renate Zygan-Maus, H.H. Wolter

Physics Letters AJan 1, 197814 citations

Compatible Statistical Interpretation of Quantum Beats

Mirjana Božić

Springer eBooksJan 1, 19970 citations

Exciton energy oscillations induced by quantum beats

Artur V. Trifonov, A. S. Kurdyubov, I. Ya. Gerlovin +5 more

In this paper, we experimentally demonstrate an oscillating energy shift of center-of-mass quantum-confined exciton levels in a semiconductor quantum well after excitation into a superposition of two quantum confined exciton states of different parity. Oscillations are observed at frequencies corresponding to the quantum beats between these states. We show that the observed effect is a manifestation of the exciton density oscillations in the real space similar to the dynamics of an electron in a Hertzian dipole. The effect is caused by the exciton-exciton exchange interaction and appears only if the excitons are in a superposition quantum state. This effect exists until the Raman coherence in the interacting excitons has decayed. This effect may be harnessed for quantum technologies requiring the quantum coherence of states.In this paper, we experimentally demonstrate an oscillating energy shift of center-of-mass quantum-confined exciton levels in a semiconductor quantum well after excitation into a superposition of two quantum confined exciton states of different parity. Oscillations are observed at frequencies corresponding to the quantum beats between these states. We show that the observed effect is a manifestation of the exciton density oscillations in the real space similar to the dynamics of an electron in a Hertzian dipole. The effect is caused by the exciton-exciton exchange interaction and appears only if the excitons are in a superposition quantum state. This effect exists until the Raman coherence in the interacting excitons has decayed. This effect may be harnessed for quantum technologies requiring the quantum coherence of states.

arXiv:2003.08143Physical review. B./Physical review. BNov 23, 20203 citations

We introduce methods for clock synchronization that make use of the adiabatic exchange of nondegenerate two-level quantum systems: ticking qubits. Schemes involving the exchange of

N

independent qubits with frequency $\ensuremath{\omega}$ give a synchronization accuracy that scales as ${(\ensuremath{\omega}\sqrt{N})}^{\ensuremath{-}1}$---i.e., as the standard quantum limit. We introduce a protocol that makes use of

{N}_{c}

coherent exchanges of a single qubit at frequency $\ensuremath{\omega}$, leading to an accuracy that scales as ${(\ensuremath{\omega}{N}_{c})}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}{N}_{c}$. This protocol beats the standard quantum limit without the use of entanglement, and we argue that this scaling is the fundamental limit for clock synchronization allowed by quantum mechanics. We analyze the performance of these protocols when used with a lossy channel.