Quantum Variational Optimization of Ramsey Interferometry and Atomic Clocks

Long-lived Bell states in an array of optical clock qubits

“…A crucial near-term goal in this direction is to extend these results from pairs to clusters of several-totens of atoms, and to identify and generate the particular optimal quantum states of these clusters for a clock stability measurement [37,65]. Entangling operations both before and after the interrogation time may further enhance clock stability [40,42,[66][67][68][69].…”

“…Given the control and measurements possible in modern atomic clock architectures, these systems offer the possibility of merging quantum information concepts with precision measurement. Utilizing entangling gates and protocols from quantum information science broadens the set of realizable quantum states, enabling new protocols for quantum metrology, while quantum error correcting codes have opened routes for enhanced quantum sensing in the presence of noise and imperfect quantum resources [37][38][39][40][41][42][43]. In the context of optical atomic clocks, a number of recent protocols have advanced this union as a route to quantumenhanced measurements [37,40,42,44], and, in a very recent demonstration, variational optimization of phase sensitivity at optical frequencies was implemented on a 26 ion quantum processor [44].…”

Criticality-Enhanced Quantum Sensing via Continuous Measurement

“…Such enhancement, on the one hand, can in principle be achieved by preparing individual sensor components in entangled quantum states, e.g., the Greenberger-Horne-Zeilinger (GHZ) state [7] and spinsqueezed states [6,8]. Nevertheless, such states are technically challenging to scale up and are fragile when exposed to noise [9], and is thus far restricted to a small number of components, see recent advances [10][11][12][13][14][15][16]. One the other hand, alternative strategies without direct use of entangled states open up intriguing and promising routes towards quantum-enhanced sensing with affordable technological demand, see Ref.…”

Blackbody-radiation-induced facilitated excitation of Rydberg atoms in optical tweezers

“…The imperative role of motion and most importantly the possibility to control the Rydberg motion by repulsive trapping potentials suggests a new possibility to circumvent catastrophic avalanche dephasing in one-or two-dimensional Rydberg-dressed systems: By a strong and tightly focused light-sheet potential at wavelengths chosen to trap the ground state but to quickly accelerate the contaminant atoms away from the many-body system under study, a single-atom-decay limited lifetime can be restored. This paves the way to utilize Rydberg dressing for the design of atomic Hamiltonians for the study of various quantum spin models [16][17][18] or to generate useful states for quantum metrology [51,52,59].…”