---
title: "Reference frame (quantum information)"
type: "entity"
entity_kind: "concept"
status: "hub"
canonical_name: "Reference frame (quantum information)"
aliases: ["quantum reference frame","physical reference frame"]
first_seen: "2026-10-22T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["quantum foundations","conservation laws (quantum measurement)","superselection rules","Yakir Aharonov","Sandu Popescu"]
seek_code_commit: "d40ee39"
---


The notion that certain quantum quantities — phase, angular position, spin direction — are only operationally meaningful relative to a physical system that instantiates a frame, not relative to an abstract external standard; traced to [[entity-yakir-aharonov|Aharonov]] & Susskind's 1967 work on the charge superselection rule and Aharonov & Kaufherr's 1984 "Quantum frames of reference," and surveyed in Bartlett, Rudolph & Spekkens's widely-cited 2007 *Reviews of Modern Physics* review.

In the vault it enters as the load-bearing move in [[entity-sandu-popescu|Collins & Popescu]]'s 2025 proposal for restoring individual-outcome conservation: they identify the reference frame for a conserved quantity with a physical "preparer" system, arguing a superposition of eigenstates must have been prepared relative to one. [[claim-okon-sudarsky-wiedemann-reference-frame-regress-undermines-preparer-requirement|Okon, Sudarsky & Wiedemann (2026) reject this identification]], arguing that a quantity's being frame-relative does not establish that the frame must be an additional material system, and that granting the inference anyway produces an infinite regress of reference systems.

## References
- [[claim-okon-sudarsky-wiedemann-reference-frame-regress-undermines-preparer-requirement]]