TBNQuantum
The memory cost of sequential quantum state preparation
Publication: quant-ph updates on arXiv.org
Author: Jian Li, Patryk Lipka-Bartosik
Source published: 13/11/2026, 05:00:00 UTC
Briefing created: 13/11/2026, 08:00:59 UTC
Based on a feed excerpt; full article content has not been acquired. Source evidence retrieved 13/11/2026, 07:43:25 UTC.
Briefings
A 2026 arXiv preprint investigates the memory requirements for preparing quantum systems sequentially versus collectively. It establishes that while asymptotic costs are equal under general assumptions, sequential preparation can demand unbounded memory compared to collective methods. For energy-conserving unitaries, the extra memory needed is either bounded or grows logarithmically with outputs. Under noisy operations, specific transformations require only one auxiliary qubit collectively but none sequentially. The study also identifies a $d$-dimensional memory that succeeds for $d^2$ rounds as a form of quantum catalysis.
Key points
- Sequential quantum state preparation can require an unboundedly larger memory than collective preparation under general assumptions.
- For energy-conserving unitaries, the extra memory required sequentially either remains bounded or grows logarithmically with the number of outputs.
Context
This research addresses the memory cost of preparing quantum systems one at a time, using quantum resource theories to formalize physical restrictions on memory interaction. The findings clarify the trade-offs between sequential and collective protocols, with implications for quantum device design and resource management.
Limitations
The study relies on general assumptions and specific physical restrictions like energy conservation. Results for noisy operations are conditional on specific transformation types. The paper is an arXiv preprint (v1) and does not include experimental validation or definitive conclusions.
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