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Universal Gaps for XOR Games from Estimates on Tensor Norm Ratios
Communications in Mathematical Physics ( IF 2.4 ) Pub Date : 2020-03-07 , DOI: 10.1007/s00220-020-03688-2
Guillaume Aubrun , Ludovico Lami , Carlos Palazuelos , Stanisław J. Szarek , Andreas Winter

We define and study XOR games in the framework of general probabilistic theories, which encompasses all physical models whose predictive power obeys minimal requirements. The bias of an XOR game under local or global strategies is shown to be given by a certain injective or projective tensor norm, respectively. The intrinsic (i.e. model-independent) advantage of global over local strategies is thus connected to a universal function r ( n , m ) called ‘projective–injective ratio’. This is defined as the minimal constant $$\rho $$ ρ such that $$\Vert \cdot \Vert _{X\otimes _\pi Y}\leqslant \rho \,\Vert \cdot \Vert _{X\otimes _\varepsilon Y}$$ ‖ · ‖ X ⊗ π Y ⩽ ρ ‖ · ‖ X ⊗ ε Y holds for all Banach spaces of dimensions $$\dim X=n$$ dim X = n and $$\dim Y=m$$ dim Y = m , where $$X\otimes _\pi Y$$ X ⊗ π Y and $$X \otimes _\varepsilon Y$$ X ⊗ ε Y are the projective and injective tensor products. By requiring that $$X=Y$$ X = Y , one obtains a symmetrised version of the above ratio, denoted by $$r_s(n)$$ r s ( n ) . We prove that $$r(n,m)\geqslant 19/18$$ r ( n , m ) ⩾ 19 / 18 for all $$n,m\geqslant 2$$ n , m ⩾ 2 , implying that injective and projective tensor products are never isometric. We then study the asymptotic behaviour of r ( n , m ) and $$r_s(n)$$ r s ( n ) , showing that, up to log factors: $$r_s(n)$$ r s ( n ) is of the order $$\sqrt{n}$$ n (which is sharp); r ( n , n ) is at least of the order $$n^{1/6}$$ n 1 / 6 ; and r ( n , m ) grows at least as $$\min \{n,m\}^{1/8}$$ min { n , m } 1 / 8 . These results constitute our main contribution to the theory of tensor norms. In our proof, a crucial role is played by an ‘ $$\ell _1/\ell _2/\ell _{\infty }$$ ℓ 1 / ℓ 2 / ℓ ∞ trichotomy theorem’ based on ideas by Pisier, Rudelson, Szarek, and Tomczak-Jaegermann. The main operational consequence we draw is that there is a universal gap between local and global strategies in general XOR games, and that this grows as a power of the minimal local dimension. In the quantum case, we are able to determine this gap up to universal constants. As a corollary, we obtain an improved bound on the scaling of the maximal quantum data hiding efficiency against local measurements.

中文翻译:

来自张量范数比估计的异或游戏的通用差距

我们在一般概率理论的框架内定义和研究 XOR 游戏,该框架包含所有预测能力符合最低要求的物理模型。局部或全局策略下的 XOR 游戏的偏差分别由某个内射或投影张量范数给出。因此,全局相对于局部策略的内在(即独立于模型的)优势与称为“投影-注入比”的通用函数 r ( n , m ) 相关。这被定义为最小常数 $$\rho $$ ρ 使得 $$\Vert \cdot \Vert _{X\otimes _\pi Y}\leqslant \rho \,\Vert \cdot \Vert _{X\ otimes _\varepsilon Y}$$ ‖ · ‖ X ⊗ π Y ⩽ ρ ‖ · ‖ X ⊗ ε Y 对所有维度为 $$\dim X=n$$ dim X = n 和 $$\dim Y 的 Banach 空间成立=m$$ 昏暗 Y = m , 其中 $$X\otimes _\pi Y$$ X ⊗ π Y 和 $$X \otimes _\varepsilon Y$$ X ⊗ ε Y 是投影和单射张量积。通过要求 $$X=Y$$ X = Y ,可以获得上述比率的对称版本,由 $$r_s(n)$$ rs ( n ) 表示。我们证明 $$r(n,m)\geqslant 19/18$$ r ( n , m ) ⩾ 19 / 18 对于所有 $$n,m\geqslant 2$$n , m ⩾ 2 ,暗示单射和投影张量积永远不是等距的。然后我们研究 r ( n , m ) 和 $$r_s(n)$$ rs ( n ) 的渐近行为,表明,直到对数因子: $$r_s(n)$$ rs ( n ) 是订单 $$\sqrt{n}$$ n (这是尖锐的);r ( n , n ) 至少是 $$n^{1/6}$$ n 1 / 6 的顺序;并且 r ( n , m ) 至少增长为 $$\min \{n,m\}^{1/8}$$ min { n , m } 1 / 8 。这些结果构成了我们对张量范数理论的主要贡献。在我们的证明中,基于 Pisier、Rudelson、Szarek 和 Tomczak 的思想的“$$\ell _1/\ell _2/\ell _{\infty }$$ ℓ 1 / ℓ 2 / ℓ ∞ 三分定理”发挥了关键作用- 耶格曼。我们得出的主要操作结果是,在一般 XOR 游戏中,局部和全局策略之间存在普遍差距,并且这种差距随着最小局部维度的力量而增长。在量子情况下,我们能够确定这个差距直到普遍常数。作为推论,我们获得了针对局部测量的最大量子数据隐藏效率缩放的改进界限。我们得出的主要操作结果是,在一般 XOR 游戏中,局部和全局策略之间存在普遍差距,并且这种差距随着最小局部维度的力量而增长。在量子情况下,我们能够确定这个差距直到普遍常数。作为推论,我们获得了针对局部测量的最大量子数据隐藏效率缩放的改进界限。我们得出的主要操作结果是,在一般 XOR 游戏中,局部和全局策略之间存在普遍差距,并且这种差距随着最小局部维度的力量而增长。在量子情况下,我们能够确定这个差距直到普遍常数。作为推论,我们获得了针对局部测量的最大量子数据隐藏效率缩放的改进界限。
更新日期:2020-03-07
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