Executive Summary
The Aharonov-Bohm (AB) effect demonstrates that a quantum particle can acquire a physical phase shift while traversing a region with zero classical field strength, proving the physical reality of the underlying potentials. We propose a novel, low-cost experiment to search for an analogous effect: a differential phase shift in an atom interferometer induced by a controllable, non-electromagnetic potential. This potential, hypothesized by certain unified frameworks, can be modulated locally using a weak, non-resonant radio-frequency (RF) field. The proposed experiment would leverage the unprecedented sensitivity of your long-baseline atom interferometer to search for a phase shift that scales linearly with the applied RF power—a distinct signature that cannot be explained by known electromagnetic effects like the AC Zeeman shift. A positive result would constitute the discovery of a new fundamental interaction. A null result would place the world's most stringent constraints on such theories. This high-impact search can be implemented with a minor, low-cost hardware addition and a modified data acquisition sequence.
1. Scientific Motivation: Beyond the Aharonov-Bohm Effect
The Aharonov-Bohm effect fundamentally shifted our understanding of locality in physics. It proved that the local state of a quantum system is determined not just by the local fields (E, B), but by the non-local potentials (Aµ, φ). The core principle is that the phase evolution of a wavefunction, exp(-iEt/ħ), is modified by these potentials.
We hypothesize that this principle may extend beyond electromagnetism. Several theoretical frameworks aiming to unify quantum mechanics and gravity (such as discrete spacetime or emergent gravity models) posit the existence of a fundamental scalar field, Ω(x,t), which dictates the local rate of quantum phase evolution. This field is analogous to the temporal component of a four-vector potential, but it is not electromagnetic in origin. While this field is typically constant (Ω₀), these frameworks predict it can be locally modulated by specific types of interaction.
Just as a magnetic vector potential induces a phase shift ΔΦ ∝ ∮ A ⋅ dl in a region with B=0, a gradient in this hypothesized Ω field could induce a differential phase shift in an atom interferometer, even in the complete absence of classical forces on the atoms. Your instrument provides the first-ever opportunity to search for such an effect with the required sensitivity.
2. The Core Hypothesis & Testable Prediction
Our central hypothesis is that the local phase evolution rate (ω_eff) can be boosted by an "observational interaction strength" (O). The theory predicts that a weak, non-resonant RF magnetic field can serve as a controllable source of O. The resulting boost in the local phase evolution rate is given by:
Δω_eff = ω₀ * (η' * O²), where O² ∝ P_RF
Here, η' is a new fundamental coupling constant and P_RF is the power of the applied RF field. When applied to one arm of an atom interferometer over an interaction time T, this leads to a clear, testable prediction for a differential phase shift ΔΦ:
ΔΦ_predicted = (Δω_eff) * T ∝ η' * T * P_RF
The key signature is a linear relationship between the measured phase shift and the applied RF power. This provides a clean, background-free signal, as known EM effects like the AC Zeeman shift scale differently (typically with B_RF², which is proportional to P_RF, but with a different frequency dependence and magnitude).
3. Proposed Experimental Implementation
We propose a simple modification to your existing experimental setup and sequence.
- Hardware Addition: A compact, cylindrical RF coil (solenoid), enclosed in multi-layer mu-metal shielding to contain the magnetic field. The module would be installed around the vacuum tube of one of the interferometer arms.
- Protocol: The standard experimental sequence would be augmented. During the atom's transit, the RF coil around Arm A is energized with a specific power P_RF. The process is repeated for a range of P_RF values to map the ΔΦ vs. P_RF relationship.
4. Predicted Signal & Sensitivity Analysis
While baseline theoretical estimates place the signal at the edge of current sensitivity (~10⁻¹⁵ rad), the theory also suggests the possibility of resonant enhancement if the RF probe frequency matches a natural mode of the spacetime substrate. A scan across frequencies and powers is therefore the primary goal. Even a null result would be scientifically invaluable, placing an upper limit on the η' coupling constant that is orders of magnitude better than any current constraint.
5. Systematic Errors and Mitigation
The primary systematic concern is the AC Zeeman effect from residual, unshielded B_RF fields. This will be mitigated via (1) high-performance magnetic shielding, (2) choosing a non-resonant RF frequency, (3) the differential measurement cancelling common-mode effects, and (4) precisely calculating the expected Zeeman shift and searching for a signal *in excess* of this known effect.
6. Potential Impact & Alignment with Mission Goals
This proposal is perfectly aligned with your mission to search for new, fundamental physics beyond the Standard Model. A positive detection would be a monumental discovery of a new fundamental interaction. A null result would provide world-leading constraints on a major class of unified theories. This high-impact, low-cost search represents a unique opportunity to leverage your instrument's groundbreaking sensitivity to explore uncharted physical territory.