Questions tagged [qma]

For question about Quantum Merlin Arthur (QMA), a computational complexity class. QMA is the 'quantum analogue' of NP, that is QMA is to BQP as NP is to P.

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Quantum Chemistry and Quantum Computing

Predicting the energy of molecules to high accuracy during the course of a chemical reaction, which in turn allows us to predict reaction rates, equilibrium geometries, transition states among others is a Quantum Chemical problem. Quantum Computing…
user3483902
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How do we understand Jordan's Lemma?

In quantum computing protocols, jordan's lemma keeps cropping up. See, for example, here: https://cims.nyu.edu/~regev/teaching/quantum_fall_2005/ln/qma.pdf For any two projectors $\phi_1$, $\phi_2$, there exists an orthogonal decomposition of the…
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Better "In-Place" Amplification of QMA

$\def\braket#1#2{\langle#1|#2\rangle}\def\bra#1{\langle#1|}\def\ket#1{|#1\rangle}$ In MW05 the authors demonstrate so-called "in-place" amplitude amplification for QMA, exhibiting a method for Arthur to amplify his success probability without…
bean
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Quantum proof for the group non-membership problem

Group non-membership problem: Input: Group elements $g_1,..., g_k$ and $h$ of $G$. Yes: $h \not\in \langle g_1, ..., g_k\rangle$ No: $h\in \langle g_1, ..., g_k\rangle$ Notation: $\langle g_1, ..., g_k\rangle$ is the subgroup generated by…
Sanchayan Dutta
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Relation between $\mathrm{QMA}$ and $\mathrm{P^{QMA}}$

What is the relation between $\mathrm{QMA}$ and $\mathrm{P^{QMA}}$ and how do we prove it? Are these classes equal?
BlueLagoon
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How can I show that $\mathsf{QMA}\subseteq \mathsf{PSPACE}$

Lately I have seen the claim that $\mathsf{QMA}\subseteq \mathsf{PSPACE}$, and I wonder how can it be proved. Thanks
omerna
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Upper Bounds for QMA Quantum Merlin Arthur, and QMA(k)

QMA (Quantum Merlin Arthur), is the quantum analog of NP, and QMA(k) is the class with $k$ Merlins. These are important classes when studying Quantum Complexity theory. QMA(k) is QMA with $k$ unentangled provers ($k$ Merlins), or BQP verfiers. These…
user3483902
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How is a promise gap related to a spectral gap?

In linear algebra one often concerns oneself with the spectral gap of a given matrix, which may be defined as the difference between the smallest and second-smallest eigenvalue (or, depending on convention and context, between the largest and…
Mark Spinelli
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Self reducibility of QCMA problems

Self reducibility is when search version of the problems in a language reduce to decision versions of the same problems. NP-complete problems are self reducible. Are QCMA complete problems self reducible?
BlackHat18
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Marriott-Watrous style amplification with a quantum input

$\def\braket#1#2{\langle#1|#2\rangle}\def\bra#1{\langle#1|}\def\ket#1{|#1\rangle}$ In MW05 the authors demonstrate so-called "in-place" amplitude amplification for QMA, exhibiting a method for Arthur to amplify his success probability without…
bean
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What classical public key cryptography protocols exist for which hacking is QMA complete or QMA hard?

Such a public key cryptosystem would be "quantum safe" in the sense that quantum computers cannot efficiently solve QMA hard problems.
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The complexity of LH with constant gap

Kitaev's quantum equivalent of the Cook-Levin Theorem, provides a polynomial time classical reduction from a QMA verification circuit to a sum $H$ of local hamiltonians, such that the least eigenvalue of $H$ is either $\leq a$ or $\geq b$, with…
J.Ask
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Did Kitaev prove the QMA-completeness of the Local Hamiltonian problem while on a flight to Chicago?

I believe the first publication of the proof of the QMA-completeness of the Local Hamiltonian Problem is as portions of a chapter in the book Classical and Quantum Computation, by Kitaev, Shen, and Vyilyi, published in Russian in 1999 (with an…
Mark Spinelli
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For the Local Hamiltonian Problem, how is soundness proved if Arthur uses phase estimation on the putative ground state provided by Merlin?

Recall that showing QMA-completeness of the Local Hamiltonian Problem includes showing that the problem is both (A) in (promise) QMA and (B) QMA hard. QMA hardness is usually shown with a neat bespoke circuit-to-Hamiltonian construction that…
Mark Spinelli
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How useful is it to know the ground state energy of an arbitrary $k$-local Hamiltonian, if Nature herself can never find such energy?

We know that the $2$-local Hamiltonian problem is (promise) QMA-complete, which under the reasonable assumption that BQP$\subsetneq$QMA implies that no fast quantum algorithm exists to determine the eigenstate, much less the energy, of the ground…
Mark Spinelli
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