We propose a quantum-enhanced sensing scheme for the detection of wave-like dark matter and high-frequency gravitational waves using two-dimensional ion crystals in a Penning trap. The protocol employs spin-motion squeezed states to improve the signal-to-noise ratio and enable a super-Heisenberg scaling with respect to the number of ions over a broad parameter range. We analyze the sensitivity of the protocol to representative wave-like dark matter candidates, including the axion-like particle and the dark photon, as well as to high-frequency gravitational waves, taking into account the decoherence and dephasing of the ion spins. Our results indicate that two-dimensional ion crystals and this new protocol provide a promising platform for probing previously unexplored parameter space in searches for light dark matter and high-frequency gravitational waves.
We propose a quantum-enhanced sensing scheme for the detection of wave-like dark matter and high-frequency gravitational waves using two-dimensional ion crystals in a Penning trap. The protocol employs spin-motion squeezed states to improve the signal-to-noise ratio and enable a super-Heisenberg scaling with respect to the number of ions over a broad parameter range. We analyze the sensitivity of the protocol to representative wave-like dark matter candidates, including the axion-like particle and the dark photon, as well as to high-frequency gravitational waves, taking into account the decoherence and dephasing of the ion spins. Our results indicate that two-dimensional ion crystals and this new protocol provide a promising platform for probing previously unexplored parameter space in searches for light dark matter and high-frequency gravitational waves.
This work investigates the use of linear Paul traps as quantum sensors for detecting megahertz gravitational waves. Single-ion configurations exploit graviton-photon conversion in the presence of external magnetic fields, while two-ion systems use relative-motion excitations, which do not require magnets, to distinguish gravitational waves from axion dark matter. Furthermore, we show that entanglement of N vibrational qubits enhances the signal probability by a factor of N 2 , improving sensitivity beyond the standard quantum limit.
We present the design and status of a detector to search for axions and axion-like particles in the galactic halo using quantum-enhanced interferometry. The operating principle is related to previously reported ideas, but aims for axions in the mass range from 10−16 eV up to 10−8 eV. We also show how to apply squeezed states of light to enhance the sensitivity similar to the gravitational-wave detectors. This experiment has the potential to be further scaled up to a multi-kilometre long detector and to then set constraints of the axion-photon coupling coefficient of ∼ 10−18 GeV−1 for axion masses of 10−16 eV, or detect a signal.
A detection method for high-frequency gravitational waves using two-dimensional ion crystals is investigated. Gravitational waves can resonantly excite the drumhead modes of the ion crystal, particularly the parity-odd modes. In the optical dipole force protocol, entanglement between the drumhead modes and the collective spins transfers the excitation of the drumhead modes to the rotation of the total spin. Furthermore, gravitational wave detection beyond the standard quantum limit becomes possible as a squeezed spin state is generated through this entanglement. The sensitivity gets better with a larger ions crystals as well as a larger number of the ions. Future realization of large ion crystals can significantly improve the sensitivity to gravitational waves in the 10 kHz to 10 MHz region.
We propose a quantum sensing protocol for coupled qubit-oscillator systems that enhances the sensitivity by exploiting a geometric phase for dark matter searches. Instead of letting the cavity evolve freely under a weak dark matter background, we combine large coherent displacements and squeezing operations within the evolution protocol, thereby mapping the signal onto an enhanced quantum phase determined by the geometric area enclosed in phase space. Relative to the conventional free-evolution scheme, the protocol enhances the quantum Fisher information and improves the projected sensitivities to cavity-based detection of dark-photon and axion dark matter.
We explore how recent advances in the manipulation of single-ion wave packets open new avenues for detecting weak magnetic fields sourced by ultralight dark matter. A trapped ion in a “Schrödinger’s cat” state can be prepared with its spin and motional degrees of freedom entangled and be used as a matter-wave interferometer that is sensitive to the Aharonov-Bohm-like phase shift accumulated by the ion over its trajectory. The result of the spin-motion entanglement is a parametrically enhanced sensitivity to weak magnetic fields as compared with an unentangled ion in a trap. Taking into account the relevant boundary conditions, we demonstrate that a single trapped ion can probe unexplored regions of kinetically mixed dark-photon dark matter parameter space in the 10 − 15 eV ≲ m A ′ ≲ 10 − 14 eV mass window. We also show how such a table-top quantum device will also serve as a complementary probe of axionlike particle dark matter in the same mass window.
We propose an array of Ramsey-type interferometers using N superposition states, (∣0⟩+∣1⟩)⊗N, as a sensor to detect wave-like dark matter. After exposure to the dark matter wave, which induces coherent qubit transitions, the signal is the imbalance between the numbers of 0 and 1 outcomes. The signal-to-noise ratio in this scheme is proportional to Nα2, where α is the coupling of dark matter to the qubits, and thus the sensitivity to the coupling scales as δα∼1/N. For comparison, in the detection scheme based on the Rabi-type transition, ∣0⟩→∣1⟩, this scaling is achieved only when N highly entangled qubits are used. Since the Ramsey-type measurement does not require entangled states, one can consider much larger N by simply placing a large number of qubits within the de Broglie wavelength of the dark matter. We demonstrate that, using trapped-ion qubits in linear Paul traps as the sensor, the projected sensitivity to the coupling matches or surpasses existing laboratory, astrophysical, and cosmological bounds for N≳106-108. We also evaluate its sensitivity to high-frequency gravitational waves. Our general framework should, in principle, be useful for other quantum sensing platforms.