arXiv subjects

Antonis Delakouras

Publications and source records attributed to Antonis Delakouras.

3 recordsLinked to original sources

arXiv2025

Fundamental error bound for entanglement generation between interacting Rydberg atoms

We analytically derive the lower error bound for the preparation of any maximally entangled state of two atoms involving Rydberg-state interactions. This fundamental bound represents the minimum achievable error $E \geq ( 1 + \pi/2 ) \Gamma/B$ due to spontaneous decay $\Gamma$ of the Rydberg states and their finite interaction strength $B$, assuming that all other technical errors can be eliminated. Using quantum optimal control methods, we identify laser pulses for preparing a maximally entangled state of a pair of atomic qubits with an error only $1\%$ above the derived fundamental bound.

quant-ph↗

arXiv2025

Multi-qubit Rydberg gates between distant atoms

We propose an efficient protocol to realize multi-qubit gates in arrays of neutral atoms. The atoms encode qubits in the long-lived hyperfine sublevels of the ground electronic state. To realize the gate, we apply a global laser pulse to transfer the atoms to a Rydberg state with strong blockade interaction that suppresses simultaneous excitation of neighboring atoms arranged in a star-graph configuration. The number of Rydberg excitations, and thereby the parity of the resulting state, depends on the multiqubit input state. Upon changing the sign of the interaction and de-exciting the atoms with an identical laser pulse, the system acquires a geometric phase that depends only on the parity of the excited state, while the dynamical phase is completely canceled. Using single qubit rotations, this transformation can be converted to the C$_k$Z or C$_k$NOT quantum gate for $k+1$ atoms. We also present extensions of the scheme to implement quantum gates between distant atomic qubits connected by a quantum bus consisting of a chain of atoms.

quant-ph↗

arXiv2022

Production of Fock Mixtures in Trapped Ions for Motional Metrology

We present a protocol to produce a class of non-thermal Fock state mixtures in trapped ions. This class of states features a clear metrological advantage with respect to the ground state, thus overcoming the standard quantum limit without the need for full sideband cooling and Fock-state preparation on a narrow electronic transition. The protocol consists in the cyclic repetition of red-sideband, measurement and preparation laser pulses. By means of the Kraus map representation of the protocol, it is possible to relate the length of the red sideband pulses to the specific class of states that can be generated. With the help of numerical simulations, we analyze the parametric regime where these states can be reliably reproduced.

quant-ph↗