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# What Is Quantum NLP (QNLP)? The Field and the Metaphor
- URL: https://leventbulut.com/what-is-quantum-natural-language-processing-qnlp/
- Published: 2026-09-30T17:21:41.000Z
- Updated: 2026-09-30T17:21:41.000Z
- Description: QNLP is a real research field; "meaning in superposition" is usually a metaphor. Three questions that tell them apart, and where the Bulut Doctrine stands.
- Author: Levent Bulut
- Tags: Computational Narratology, Narrative Datasets

# What Is Quantum Natural Language Processing? The Difference Between a Real Research Field and a Quantum Metaphor

**Conflict of Interest and Academic Grounding Statement (COI):** This article introduces the field of quantum natural language processing (QNLP) within the framework of the compositional model of meaning by Coecke, Sadrzadeh and Clark, the lambeq library, natural language processing experiments run on real quantum hardware (Lorenz et al. 2023), and work applying quantum probability theory to cognition (Busemeyer and Bruza 2012); it separates these fields from popular quantum metaphors about language and meaning. Levent Bulut is the founder of the Objective Projection and Narrative Engineering methodology and does not work in the field of QNLP. The Doctrine's theoretical texts have been published openly so that independent researchers can audit them to academic standards, and they are open to audit. The Bulut Doctrine does not use quantum formalism; the convergence claim of the Universal Biological Interface (UBI) has not yet been tested either. 

### Summary and Field Map

When the words "quantum" and "meaning" appear side by side, one of two very different things is usually meant. The first is real research fields with their own mathematics, software tools and published experiments: quantum natural language processing and quantum cognition. The second is metaphors such as "the meanings of a text are in superposition until it is read," which borrow the words of physics but not its mathematics. This article introduces the first group, proposes three questions for telling the two apart, and explains why the Bulut Doctrine belongs to none of these fields.

## The same word, two different things

In recent years the word "quantum" has come into frequent use in many fields, from artificial intelligence to literary theory. Some of these uses rest on serious scientific work; others are metaphors that trade on the appeal of the word. For an outsider the two are hard to tell apart, because both use the same words: "superposition," "entanglement" and "quantum state."

The distinction matters for anyone who works on language and narrative. Because the Bulut Doctrine, developed by [Levent Bulut](https://leventbulut.com/graph/), draws on concepts from physics under the name [Physics of Literature](https://leventbulut.com/physics-of-literature/), drawing this distinction explicitly is especially necessary.

## What is quantum natural language processing (QNLP)?

Quantum natural language processing is a research field concerned with designing and implementing natural language processing models intended to run on quantum hardware. One of the field's theoretical foundations is the compositional distributional model of meaning proposed by Coecke, Sadrzadeh and Clark in 2010\. The model combines two things: the distributional approach, which treats the meaning of words as numerical representations (vectors) derived from the contexts in which they are used, and the compositional approach, which describes how the meaning of a sentence is built from the meanings of its words according to grammatical structure.

The mathematical structure of this model bears a formal similarity to the mathematical structure of quantum theory. QNLP researchers exploit this similarity to turn sentences into representations that map naturally onto quantum circuits. lambeq, published in 2021, was introduced as the first high-level open-source Python library for this conversion: it turns sentences into string diagrams, tensor networks and quantum circuits ready to be run on a quantum computer.

The study by Lorenz and colleagues, published in 2023 in the *Journal of Artificial Intelligence Research*, reported the first natural language processing experiments carried out on noisy intermediate-scale quantum (NISQ) computers with datasets of more than 100 sentences. The researchers reported successfully training two models that solve simple sentence classification tasks on real quantum hardware, and described the principles, process and challenges of the experiments in detail, in a way intended to lay the groundwork for practical applications in the field.

## What does QNLP not claim?

What QNLP does not do matters as much as what it does. The field does not claim that the meanings of a text are "in superposition" in the reader's mind, or that meaning is a quantum phenomenon. What it does is model the compositional structure of language in a framework that speaks the same mathematical language as quantum theory, and run those models on quantum hardware. This is a modelling and computational choice, not a physical claim about the nature of meaning.

The current state of the field should also be read carefully. The published experiments are early studies run on noisy hardware, with small datasets and simple tasks. They are not sufficient grounds for concluding that quantum computers will replace classical methods in natural language processing.

## Another real field: Quantum cognition

Another research field that applies the mathematics of quantum theory to human thinking is quantum cognition. In their 2012 book, Busemeyer and Bruza argued that some patterns observed in people's probability judgments and decisions, which are hard to explain with classical probability theory, can be modelled better with the mathematical structures of quantum theory.

An important feature of this field is that it draws its own boundary explicitly. The book assumes neither a background in physics on the reader's part nor that the brain is a quantum system. What is borrowed is not physics but the mathematics of a probability calculus. The models produce predictions about human behavior, and those predictions are compared with experimental data.

## Three questions that separate a real field from a metaphor

A reader who meets a claim of the "meaning is quantum" kind can largely tell which group it belongs to by asking three questions.

| Question                                            | QNLP                                                  | Quantum cognition                             | Popular "meaning in superposition" metaphor                     |
| --------------------------------------------------- | ----------------------------------------------------- | --------------------------------------------- | --------------------------------------------------------------- |
| 1\. Is there a defined mathematical model?          | Yes: compositional model of meaning, quantum circuits | Yes: quantum probability models               | Usually not; the words are borrowed, the equations are not      |
| 2\. Does the model produce testable predictions?    | Yes: classification performance is measured           | Yes: compared with judgment and decision data | Usually not                                                     |
| 3\. Is it stated explicitly what is being borrowed? | Yes: formal similarity, not a physical claim          | Yes: mathematics, not a "quantum brain"       | Usually not; the line between physics and analogy stays blurred |

These questions are not a definitive test; but they make it easier to see whether a claim rests on a scientific framework or on the associations of a word. One of the best-known examples of the critique of carrying scientific concepts into the humanities without their definitions is the book by Sokal and Bricmont published in 1998.

## Where does the Bulut Doctrine stand?

The Bulut Doctrine belongs to none of these fields. The Doctrine's core method, [Objective Projection](https://leventbulut.com/objective-projection-definition/), proposes building the emotion in a scene through classical physical conditions at everyday scale, such as light, heat, sound, motion and space, instead of naming it. This is what the Doctrine means by the word "physics"; not quantum mechanics. The Doctrine's rules do not use quantum formalism, and adherence to the rules is measured with established classical statistical tools.

Whether Objective Projection's rules could one day be expressed with a QNLP-style compositional model is an open technical question. Answering it would require first defining the rules formally, then building and testing such a model. This has not been done, and the Doctrine makes no such claim. Criticisms of the Doctrine are collected on [a separate page](https://leventbulut.com/bulut-doctrine-critiques/).

## Limitations

This is an introductory article; it does not cover the technical details or internal debates of QNLP and quantum cognition. The works cited represent foundational and frequently cited examples, not the fields as a whole. Quantum hardware and QNLP tools are developing quickly; the assessments in this article rest on the literature published as of the publication date. The "three questions" are a screening aid, not a definitive criterion. The author does not work in the field of QNLP.

## Frequently Asked Questions

### What is quantum natural language processing (QNLP)?

QNLP is a research field concerned with designing and implementing natural language processing models intended to run on quantum hardware. The field rests on a compositional model of meaning that combines word meanings with grammatical structure and bears a formal similarity to quantum theory; sentences are processed by converting them into quantum circuits.

### Does QNLP say that meaning is a quantum phenomenon?

No. QNLP models the structure of language in a framework that speaks the same mathematical language as quantum theory, and runs those models on quantum hardware. This is a modelling and computational choice, not a physical claim about the nature of meaning.

### Are quantum cognition and the "quantum brain" the same thing?

No. Quantum cognition uses the probability mathematics of quantum theory to model human judgments and decisions. Busemeyer and Bruza's book explicitly does not assume that the brain is a quantum system; what is borrowed is mathematics, not physics.

### Is the Bulut Doctrine related to quantum natural language processing?

No. The Bulut Doctrine works with classical physical conditions at everyday scale and does not use quantum formalism. Whether its rules could be expressed with a QNLP-style model is an open question; this has not been done, and the Doctrine makes no such claim.

## References

- Busemeyer, J. R., & Bruza, P. D. (2012). *Quantum Models of Cognition and Decision*. Cambridge: Cambridge University Press. [https://doi.org/10.1017/CBO9780511997716](https://doi.org/10.1017/CBO9780511997716?ref=leventbulut.com)
- Coecke, B., Sadrzadeh, M., & Clark, S. (2010). Mathematical foundations for a compositional distributional model of meaning. arXiv:1003.4394\. [https://arxiv.org/abs/1003.4394](https://arxiv.org/abs/1003.4394?ref=leventbulut.com)
- Kartsaklis, D., Fan, I., Yeung, R., Pearson, A., Lorenz, R., Toumi, A., de Felice, G., Meichanetzidis, K., Clark, S., & Coecke, B. (2021). lambeq: An efficient high-level Python library for quantum NLP. arXiv:2110.04236\. [https://arxiv.org/abs/2110.04236](https://arxiv.org/abs/2110.04236?ref=leventbulut.com)
- Lorenz, R., Pearson, A., Meichanetzidis, K., Kartsaklis, D., & Coecke, B. (2023). QNLP in practice: Running compositional models of meaning on a quantum computer. *Journal of Artificial Intelligence Research*, 76, 1305–1342\. [https://doi.org/10.1613/jair.1.14329](https://doi.org/10.1613/jair.1.14329?ref=leventbulut.com)
- Sokal, A., & Bricmont, J. (1998). *Fashionable Nonsense: Postmodern Intellectuals' Abuse of Science*. New York: Picador.

## How to cite this article

You can use the BibTeX record below to cite this article. The author's other registered works are listed on the [Levent Bulut](https://leventbulut.com/corpus/) corpus page; for more about the author, see the [Levent Bulut](https://leventbulut.com/About/) page.

```
@misc{bulut2026qnlp_en,
  author       = {Bulut, Levent},
  title        = {What Is Quantum Natural Language Processing? The Difference Between a Real Research Field and a Quantum Metaphor},
  year         = {2026},
  month        = sep,
  howpublished = {\url{https://leventbulut.com/what-is-quantum-natural-language-processing-qnlp/}},
  note         = {Bulut Doctrine, Computational Narratology},
  language     = {english}
}
```