Radio-frequency receiver pumped to high-azimuthal Rydberg states
A radio-frequency receiver achieves high sensitivity by pumping atoms to high-azimuthal ( ≥3) Rydberg states. A vapor cell contains quantum particles (e.g., cesium atoms). A laser system provides probe, dressing, and coupling beams to pump the quantum particles to a first Rydberg state having a high-azimuthal quantum number ≥3. A local oscillator drives an electric field in the vapor cell at a local oscillator frequency, which is imposed on a distribution of quantum particles between the first Rydberg state and a second Rydberg state. An incident RF signal field interferes with the local oscillator field, imposing an oscillation in the distribution at a beat or difference frequency and, consequently, on the intensity of the probe beam. The beat frequency component of the intensity of the probe beam is detected, and the detection signal is demodulated to extract information originally in the RF signal.
1. A radio-frequency (RF) receiver comprising:
a vapor cell containing a vapor of quantum particles;
a laser system for pumping the quantum particles to a first Rydberg state, the first Rydberg state being a high-azimuthal Rydberg state with an azimuthal quantum number ≥3;
an electric field system for providing an electric field within the vapor cell, the electric field including a time varying component having a frequency of VLO, a distribution of the quantum particles in the first Rydberg state and in a second Rydberg state varying at the frequency VLO, wherein an incident RF signal having an RF frequency of VRF interferes to yield a beat frequency ΔRF that is imposed on the distribution of the quantum particles in the first Rydberg state and in the second Rydberg state; and
a detection system for detecting the incident RF signal based on the beat frequency.
2. The radio-frequency receiver of claim 1 , wherein the laser system includes a probe laser for providing a probe beam transiting the vapor cell, the detection system detecting the incident RF signal based on at least one of the probe beam or fluorescence resulting from decay of the quantum particles from the first Rydberg state to a ground state.
3. The radio-frequency receiver of claim 2 , wherein the laser system also includes a coupling laser and at least one dressing laser, the probe laser, the dressing laser and the coupling laser cooperating to pump the quantum particles to the first Rydberg state.
4. The radio-frequency receiver of claim 1 , wherein the vapor cell has a volume not exceeding 1 cubic centimeter.
5. The radio-frequency receiver of claim 1 , wherein the RF frequency of the incident RF signal is at least 10 MHz and not more than 40 GHz.
6. The radio-frequency receiver of claim 1 , wherein the second Rydberg state is a high-azimuthal Rydberg state with an azimuthal quantum number ≥4.
7. The radio-frequency receiver of claim 1 , wherein the second Rydberg state is a low-azimuthal Rydberg state with an azimuthal quantum number ≥2.
8. A radio-frequency receiver method comprising:
pumping quantum particles to a first Rydberg state using a laser system, the first Rydberg state being a high-azimuthal Rydberg state with an azimuthal quantum number ≥3;
generating an oscillating electric field having a frequency VLO withim a vapor cell, a distribution of the quantum particles in the first Rydberg state and in a second Rydberg state varying at the frequency VLO;
receiving an incident RF signal having an RF frequency VRF, wherein VLO=VRF±ΔRF, ΔRF being a beat frequency, the incident RF signal interfering with the oscillating electric field to yield the beat frequency ΔRF that is imposed on the distribution of the quantum particles in the first Rydberg state and in the second Rydberg state; and
detecting the incident RF signal based on the beat frequency.
9. The method of claim 8 , wherein the laser system includes a probe laser for providing a probe beam transiting the vapor cell, and wherein the detecting further includes:
detecting the incident RF signal based on at least one of the probe beam or fluorescence resulting from decay of the quantum particles from the first Rydberg state to a ground state.
10. The method of claim 9 , wherein the laser system also includes a coupling laser and at least one dressing laser, the probe laser, the dressing laser and the coupling laser cooperating to pump the quantum particles to the first Rydberg state.
11. The method of claim 8 , wherein the vapor cell has a volume not exceeding 1 cubic centimeter.
12. The method of claim 8 , wherein the RF frequency of the incident RF signal is at least 10 MHz and not more than 40 GHz.
13. The method of claim 8 , wherein the pumping also includes using a dressing beam to transition quantum particles from an excited state to a dressed state and using a coupling beam to transition quantum particles from the excited state or another dressed state to the first Rydberg state.
14. The method of claim 8 , wherein the second Rydberg state is a high-azimuthal Rydberg state with an azimuthal quantum number ≥4.
15. The method of claim 8 , wherein the second Rydberg state is a low-azimuthal Rydberg state with an azimuthal quantum number ≥2.