The time qubit

• URL: http://arxiv.org/abs/2511.07220v1
• Date: Mon, 10 Nov 2025 15:42:41 GMT
• Title: The time qubit
• Authors: Yakov Bloch,
• Abstract summary: A spin precessing in a magnetic field is often used as a quantum clock, for example in tunneling-time measurements.<n>We show that such a clock can exist in a coherent superposition of opposite temporal orientations, treating the arrow of time as a quantum two-level system.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: A spin precessing in a magnetic field is often used as a quantum clock, for example in tunneling-time measurements. We show that such a clock can exist in a coherent superposition of opposite temporal orientations, treating the arrow of time as a quantum two-level system. A Mach-Zehnder interferometer with equal and opposite magnetic fields provides a simple implementation, enabling interference between forward and backward evolution and Bell-type tests of temporal coherence. Extending the framework to relativistic dynamics reveals that the Dirac Hamiltonian describes an intrinsic coupling between a spin qubit and a time qubit, with matter and antimatter corresponding to opposite poles on the temporal Bloch sphere.

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