//
// Variables
// --------------------------------------------------
//== Colors
//
//## Gray and brand colors for use across Bootstrap.
@gray-darker: lighten(#000, 13.5%); // #222
@gray-dark: lighten(#000, 20%); // #333
@gray: lighten(#000, 33.5%); // #555
@gray-light: lighten(#000, 60%); // #999
@gray-lighter: lighten(#000, 93.5%); // #eee
@brand-primary: #428bca;
@brand-success: #5cb85c;
@brand-info: #5bc0de;
@brand-warning: #f0ad4e;
@brand-danger: #d9534f;
//== Scaffolding
//
//## Settings for some of the most global styles.
//** Background color for `
`.
@body-bg: #fff;
//** Global text color on ``.
@text-color: @gray-dark;
//** Global textual link color.
@link-color: @brand-primary;
//** Link hover color set via `darken()` function.
@link-hover-color: darken(@link-color, 15%);
//== Typography
//
//## Font, line-height, and color for body text, headings, and more.
@font-family-sans-serif: "Helvetica Neue", Helvetica, Arial, sans-serif;
@font-family-serif: Georgia, "Times New Roman", Times, serif;
//** Default monospace fonts for ``, ``, and `
`.
@font-family-monospace: Menlo, Monaco, Consolas, "Courier New", monospace;
@font-family-base: @font-family-sans-serif;
@font-size-base: 14px;
@font-size-large: ceil((@font-size-base * 1.25)); // ~18px
@font-size-small: ceil((@font-size-base * 0.85)); // ~12px
@font-size-h1: floor((@font-size-base * 2.6)); // ~36px
@font-size-h2: floor((@font-size-base * 2.15)); // ~30px
@font-size-h3: ceil((@font-size-base * 1.7)); // ~24px
@font-size-h4: ceil((@font-size-base * 1.25)); // ~18px
@font-size-h5: @font-size-base;
@font-size-h6: ceil((@font-size-base * 0.85)); // ~12px
//** Unit-less `line-height` for use in components like buttons.
@line-height-base: 1.428571429; // 20/14
//** Computed "line-height" (`font-size` * `line-height`) for use with `margin`, `padding`, etc.
@line-height-computed: floor((@font-size-base * @line-height-base)); // ~20px
//** By default, this inherits from the ``.
@headings-font-family: inherit;
@headings-font-weight: 500;
@headings-line-height: 1.1;
@headings-color: inherit;
//== Iconography
//
//## Specify custom location and filename of the included Glyphicons icon font. Useful for those including Bootstrap via Bower.
//** Load fonts from this directory.
@icon-font-path: "../fonts/";
//** File name for all font files.
@icon-font-name: "glyphicons-halflings-regular";
//** Element ID within SVG icon file.
@icon-font-svg-id: "glyphicons_halflingsregular";
//== Components
//
//## Define common padding and border radius sizes and more. Values based on 14px text and 1.428 line-height (~20px to start).
@padding-base-vertical: 6px;
@padding-base-horizontal: 12px;
@padding-large-vertical: 10px;
@padding-large-horizontal: 16px;
@padding-small-vertical: 5px;
@padding-small-horizontal: 10px;
@padding-xs-vertical: 1px;
@padding-xs-horizontal: 5px;
@line-height-large: 1.33;
@line-height-small: 1.5;
@border-radius-base: 4px;
@border-radius-large: 6px;
@border-radius-small: 3px;
//** Global color for active items (e.g., navs or dropdowns).
@component-active-color: #fff;
//** Global background color for active items (e.g., navs or dropdowns).
@component-active-bg: @brand-primary;
//** Width of the `border` for generating carets that indicator dropdowns.
@caret-width-base: 4px;
//** Carets increase slightly in size for larger components.
@caret-width-large: 5px;
//== Tables
//
//## Customizes the `.table` component with basic values, each used across all table variations.
//** Padding for `
`s and `
`s.
@table-cell-padding: 8px;
//** Padding for cells in `.table-condensed`.
@table-condensed-cell-padding: 5px;
//** Default background color used for all tables.
@table-bg: transparent;
//** Background color used for `.table-striped`.
@table-bg-accent: #f9f9f9;
//** Background color used for `.table-hover`.
@table-bg-hover: #f5f5f5;
@table-bg-active: @table-bg-hover;
//** Border color for table and cell borders.
@table-border-color: #ddd;
//== Buttons
//
//## For each of Bootstrap's buttons, define text, background and border color.
@btn-font-weight: normal;
@btn-default-color: #333;
@btn-default-bg: #fff;
@btn-default-border: #ccc;
@btn-primary-color: #fff;
@btn-primary-bg: @brand-primary;
@btn-primary-border: darken(@btn-primary-bg, 5%);
@btn-success-color: #fff;
@btn-success-bg: @brand-success;
@btn-success-border: darken(@btn-success-bg, 5%);
@btn-info-color: #fff;
@btn-info-bg: @brand-info;
@btn-info-border: darken(@btn-info-bg, 5%);
@btn-warning-color: #fff;
@btn-warning-bg: @brand-warning;
@btn-warning-border: darken(@btn-warning-bg, 5%);
@btn-danger-color: #fff;
@btn-danger-bg: @brand-danger;
@btn-danger-border: darken(@btn-danger-bg, 5%);
@btn-link-disabled-color: @gray-light;
//== Forms
//
//##
//** `` background color
@input-bg: #fff;
//** `` background color
@input-bg-disabled: @gray-lighter;
//** Text color for ``s
@input-color: @gray;
//** `` border color
@input-border: #ccc;
//** `` border radius
@input-border-radius: @border-radius-base;
//** Border color for inputs on focus
@input-border-focus: #66afe9;
//** Placeholder text color
@input-color-placeholder: @gray-light;
//** Default `.form-control` height
@input-height-base: (@line-height-computed + (@padding-base-vertical * 2) + 2);
//** Large `.form-control` height
@input-height-large: (ceil(@font-size-large * @line-height-large) + (@padding-large-vertical * 2) + 2);
//** Small `.form-control` height
@input-height-small: (floor(@font-size-small * @line-height-small) + (@padding-small-vertical * 2) + 2);
@legend-color: @gray-dark;
@legend-border-color: #e5e5e5;
//** Background color for textual input addons
@input-group-addon-bg: @gray-lighter;
//** Border color for textual input addons
@input-group-addon-border-color: @input-border;
//== Dropdowns
//
//## Dropdown menu container and contents.
//** Background for the dropdown menu.
@dropdown-bg: #fff;
//** Dropdown menu `border-color`.
@dropdown-border: rgba(0,0,0,.15);
//** Dropdown menu `border-color` **for IE8**.
@dropdown-fallback-border: #ccc;
//** Divider color for between dropdown items.
@dropdown-divider-bg: #e5e5e5;
//** Dropdown link text color.
@dropdown-link-color: @gray-dark;
//** Hover color for dropdown links.
@dropdown-link-hover-color: darken(@gray-dark, 5%);
//** Hover background for dropdown links.
@dropdown-link-hover-bg: #f5f5f5;
//** Active dropdown menu item text color.
@dropdown-link-active-color: @component-active-color;
//** Active dropdown menu item background color.
@dropdown-link-active-bg: @component-active-bg;
//** Disabled dropdown menu item background color.
@dropdown-link-disabled-color: @gray-light;
//** Text color for headers within dropdown menus.
@dropdown-header-color: @gray-light;
//** Deprecated `@dropdown-caret-color` as of v3.1.0
@dropdown-caret-color: #000;
//-- Z-index master list
//
// Warning: Avoid customizing these values. They're used for a bird's eye view
// of components dependent on the z-axis and are designed to all work together.
//
// Note: These variables are not generated into the Customizer.
@zindex-navbar: 1000;
@zindex-dropdown: 1000;
@zindex-popover: 1060;
@zindex-tooltip: 1070;
@zindex-navbar-fixed: 1030;
@zindex-modal-background: 1040;
@zindex-modal: 1050;
//== Media queries breakpoints
//
//## Define the breakpoints at which your layout will change, adapting to different screen sizes.
// Extra small screen / phone
//** Deprecated `@screen-xs` as of v3.0.1
@screen-xs: 480px;
//** Deprecated `@screen-xs-min` as of v3.2.0
@screen-xs-min: @screen-xs;
//** Deprecated `@screen-phone` as of v3.0.1
@screen-phone: @screen-xs-min;
// Small screen / tablet
//** Deprecated `@screen-sm` as of v3.0.1
@screen-sm: 768px;
@screen-sm-min: @screen-sm;
//** Deprecated `@screen-tablet` as of v3.0.1
@screen-tablet: @screen-sm-min;
// Medium screen / desktop
//** Deprecated `@screen-md` as of v3.0.1
@screen-md: 992px;
@screen-md-min: @screen-md;
//** Deprecated `@screen-desktop` as of v3.0.1
@screen-desktop: @screen-md-min;
// Large screen / wide desktop
//** Deprecated `@screen-lg` as of v3.0.1
@screen-lg: 1200px;
@screen-lg-min: @screen-lg;
//** Deprecated `@screen-lg-desktop` as of v3.0.1
@screen-lg-desktop: @screen-lg-min;
// So media queries don't overlap when required, provide a maximum
@screen-xs-max: (@screen-sm-min - 1);
@screen-sm-max: (@screen-md-min - 1);
@screen-md-max: (@screen-lg-min - 1);
//== Grid system
//
//## Define your custom responsive grid.
//** Number of columns in the grid.
@grid-columns: 12;
//** Padding between columns. Gets divided in half for the left and right.
@grid-gutter-width: 30px;
// Navbar collapse
//** Point at which the navbar becomes uncollapsed.
@grid-float-breakpoint: @screen-sm-min;
//** Point at which the navbar begins collapsing.
@grid-float-breakpoint-max: (@grid-float-breakpoint - 1);
//== Container sizes
//
//## Define the maximum width of `.container` for different screen sizes.
// Small screen / tablet
@container-tablet: ((720px + @grid-gutter-width));
//** For `@screen-sm-min` and up.
@container-sm: @container-tablet;
// Medium screen / desktop
@container-desktop: ((940px + @grid-gutter-width));
//** For `@screen-md-min` and up.
@container-md: @container-desktop;
// Large screen / wide desktop
@container-large-desktop: ((1140px + @grid-gutter-width));
//** For `@screen-lg-min` and up.
@container-lg: @container-large-desktop;
//== Navbar
//
//##
// Basics of a navbar
@navbar-height: 50px;
@navbar-margin-bottom: @line-height-computed;
@navbar-border-radius: @border-radius-base;
@navbar-padding-horizontal: floor((@grid-gutter-width / 2));
@navbar-padding-vertical: ((@navbar-height - @line-height-computed) / 2);
@navbar-collapse-max-height: 340px;
@navbar-default-color: #777;
@navbar-default-bg: #f8f8f8;
@navbar-default-border: darken(@navbar-default-bg, 6.5%);
// Navbar links
@navbar-default-link-color: #777;
@navbar-default-link-hover-color: #333;
@navbar-default-link-hover-bg: transparent;
@navbar-default-link-active-color: #555;
@navbar-default-link-active-bg: darken(@navbar-default-bg, 6.5%);
@navbar-default-link-disabled-color: #ccc;
@navbar-default-link-disabled-bg: transparent;
// Navbar brand label
@navbar-default-brand-color: @navbar-default-link-color;
@navbar-default-brand-hover-color: darken(@navbar-default-brand-color, 10%);
@navbar-default-brand-hover-bg: transparent;
// Navbar toggle
@navbar-default-toggle-hover-bg: #ddd;
@navbar-default-toggle-icon-bar-bg: #888;
@navbar-default-toggle-border-color: #ddd;
// Inverted navbar
// Reset inverted navbar basics
@navbar-inverse-color: @gray-light;
@navbar-inverse-bg: #222;
@navbar-inverse-border: darken(@navbar-inverse-bg, 10%);
// Inverted navbar links
@navbar-inverse-link-color: @gray-light;
@navbar-inverse-link-hover-color: #fff;
@navbar-inverse-link-hover-bg: transparent;
@navbar-inverse-link-active-color: @navbar-inverse-link-hover-color;
@navbar-inverse-link-active-bg: darken(@navbar-inverse-bg, 10%);
@navbar-inverse-link-disabled-color: #444;
@navbar-inverse-link-disabled-bg: transparent;
// Inverted navbar brand label
@navbar-inverse-brand-color: @navbar-inverse-link-color;
@navbar-inverse-brand-hover-color: #fff;
@navbar-inverse-brand-hover-bg: transparent;
// Inverted navbar toggle
@navbar-inverse-toggle-hover-bg: #333;
@navbar-inverse-toggle-icon-bar-bg: #fff;
@navbar-inverse-toggle-border-color: #333;
//== Navs
//
//##
//=== Shared nav styles
@nav-link-padding: 10px 15px;
@nav-link-hover-bg: @gray-lighter;
@nav-disabled-link-color: @gray-light;
@nav-disabled-link-hover-color: @gray-light;
@nav-open-link-hover-color: #fff;
//== Tabs
@nav-tabs-border-color: #ddd;
@nav-tabs-link-hover-border-color: @gray-lighter;
@nav-tabs-active-link-hover-bg: @body-bg;
@nav-tabs-active-link-hover-color: @gray;
@nav-tabs-active-link-hover-border-color: #ddd;
@nav-tabs-justified-link-border-color: #ddd;
@nav-tabs-justified-active-link-border-color: @body-bg;
//== Pills
@nav-pills-border-radius: @border-radius-base;
@nav-pills-active-link-hover-bg: @component-active-bg;
@nav-pills-active-link-hover-color: @component-active-color;
//== Pagination
//
//##
@pagination-color: @link-color;
@pagination-bg: #fff;
@pagination-border: #ddd;
@pagination-hover-color: @link-hover-color;
@pagination-hover-bg: @gray-lighter;
@pagination-hover-border: #ddd;
@pagination-active-color: #fff;
@pagination-active-bg: @brand-primary;
@pagination-active-border: @brand-primary;
@pagination-disabled-color: @gray-light;
@pagination-disabled-bg: #fff;
@pagination-disabled-border: #ddd;
//== Pager
//
//##
@pager-bg: @pagination-bg;
@pager-border: @pagination-border;
@pager-border-radius: 15px;
@pager-hover-bg: @pagination-hover-bg;
@pager-active-bg: @pagination-active-bg;
@pager-active-color: @pagination-active-color;
@pager-disabled-color: @pagination-disabled-color;
//== Jumbotron
//
//##
@jumbotron-padding: 30px;
@jumbotron-color: inherit;
@jumbotron-bg: @gray-lighter;
@jumbotron-heading-color: inherit;
@jumbotron-font-size: ceil((@font-size-base * 1.5));
//== Form states and alerts
//
//## Define colors for form feedback states and, by default, alerts.
@state-success-text: #3c763d;
@state-success-bg: #dff0d8;
@state-success-border: darken(spin(@state-success-bg, -10), 5%);
@state-info-text: #31708f;
@state-info-bg: #d9edf7;
@state-info-border: darken(spin(@state-info-bg, -10), 7%);
@state-warning-text: #8a6d3b;
@state-warning-bg: #fcf8e3;
@state-warning-border: darken(spin(@state-warning-bg, -10), 5%);
@state-danger-text: #a94442;
@state-danger-bg: #f2dede;
@state-danger-border: darken(spin(@state-danger-bg, -10), 5%);
//== Tooltips
//
//##
//** Tooltip max width
@tooltip-max-width: 200px;
//** Tooltip text color
@tooltip-color: #fff;
//** Tooltip background color
@tooltip-bg: #000;
@tooltip-opacity: .9;
//** Tooltip arrow width
@tooltip-arrow-width: 5px;
//** Tooltip arrow color
@tooltip-arrow-color: @tooltip-bg;
//== Popovers
//
//##
//** Popover body background color
@popover-bg: #fff;
//** Popover maximum width
@popover-max-width: 276px;
//** Popover border color
@popover-border-color: rgba(0,0,0,.2);
//** Popover fallback border color
@popover-fallback-border-color: #ccc;
//** Popover title background color
@popover-title-bg: darken(@popover-bg, 3%);
//** Popover arrow width
@popover-arrow-width: 10px;
//** Popover arrow color
@popover-arrow-color: #fff;
//** Popover outer arrow width
@popover-arrow-outer-width: (@popover-arrow-width + 1);
//** Popover outer arrow color
@popover-arrow-outer-color: fadein(@popover-border-color, 5%);
//** Popover outer arrow fallback color
@popover-arrow-outer-fallback-color: darken(@popover-fallback-border-color, 20%);
//== Labels
//
//##
//** Default label background color
@label-default-bg: @gray-light;
//** Primary label background color
@label-primary-bg: @brand-primary;
//** Success label background color
@label-success-bg: @brand-success;
//** Info label background color
@label-info-bg: @brand-info;
//** Warning label background color
@label-warning-bg: @brand-warning;
//** Danger label background color
@label-danger-bg: @brand-danger;
//** Default label text color
@label-color: #fff;
//** Default text color of a linked label
@label-link-hover-color: #fff;
//== Modals
//
//##
//** Padding applied to the modal body
@modal-inner-padding: 15px;
//** Padding applied to the modal title
@modal-title-padding: 15px;
//** Modal title line-height
@modal-title-line-height: @line-height-base;
//** Background color of modal content area
@modal-content-bg: #fff;
//** Modal content border color
@modal-content-border-color: rgba(0,0,0,.2);
//** Modal content border color **for IE8**
@modal-content-fallback-border-color: #999;
//** Modal backdrop background color
@modal-backdrop-bg: #000;
//** Modal backdrop opacity
@modal-backdrop-opacity: .5;
//** Modal header border color
@modal-header-border-color: #e5e5e5;
//** Modal footer border color
@modal-footer-border-color: @modal-header-border-color;
@modal-lg: 900px;
@modal-md: 600px;
@modal-sm: 300px;
//== Alerts
//
//## Define alert colors, border radius, and padding.
@alert-padding: 15px;
@alert-border-radius: @border-radius-base;
@alert-link-font-weight: bold;
@alert-success-bg: @state-success-bg;
@alert-success-text: @state-success-text;
@alert-success-border: @state-success-border;
@alert-info-bg: @state-info-bg;
@alert-info-text: @state-info-text;
@alert-info-border: @state-info-border;
@alert-warning-bg: @state-warning-bg;
@alert-warning-text: @state-warning-text;
@alert-warning-border: @state-warning-border;
@alert-danger-bg: @state-danger-bg;
@alert-danger-text: @state-danger-text;
@alert-danger-border: @state-danger-border;
//== Progress bars
//
//##
//** Background color of the whole progress component
@progress-bg: #f5f5f5;
//** Progress bar text color
@progress-bar-color: #fff;
//** Default progress bar color
@progress-bar-bg: @brand-primary;
//** Success progress bar color
@progress-bar-success-bg: @brand-success;
//** Warning progress bar color
@progress-bar-warning-bg: @brand-warning;
//** Danger progress bar color
@progress-bar-danger-bg: @brand-danger;
//** Info progress bar color
@progress-bar-info-bg: @brand-info;
//== List group
//
//##
//** Background color on `.list-group-item`
@list-group-bg: #fff;
//** `.list-group-item` border color
@list-group-border: #ddd;
//** List group border radius
@list-group-border-radius: @border-radius-base;
//** Background color of single list items on hover
@list-group-hover-bg: #f5f5f5;
//** Text color of active list items
@list-group-active-color: @component-active-color;
//** Background color of active list items
@list-group-active-bg: @component-active-bg;
//** Border color of active list elements
@list-group-active-border: @list-group-active-bg;
//** Text color for content within active list items
@list-group-active-text-color: lighten(@list-group-active-bg, 40%);
//** Text color of disabled list items
@list-group-disabled-color: @gray-light;
//** Background color of disabled list items
@list-group-disabled-bg: @gray-lighter;
//** Text color for content within disabled list items
@list-group-disabled-text-color: @list-group-disabled-color;
@list-group-link-color: #555;
@list-group-link-hover-color: @list-group-link-color;
@list-group-link-heading-color: #333;
//== Panels
//
//##
@panel-bg: #fff;
@panel-body-padding: 15px;
@panel-heading-padding: 10px 15px;
@panel-footer-padding: @panel-heading-padding;
@panel-border-radius: @border-radius-base;
//** Border color for elements within panels
@panel-inner-border: #ddd;
@panel-footer-bg: #f5f5f5;
@panel-default-text: @gray-dark;
@panel-default-border: #ddd;
@panel-default-heading-bg: #f5f5f5;
@panel-primary-text: #fff;
@panel-primary-border: @brand-primary;
@panel-primary-heading-bg: @brand-primary;
@panel-success-text: @state-success-text;
@panel-success-border: @state-success-border;
@panel-success-heading-bg: @state-success-bg;
@panel-info-text: @state-info-text;
@panel-info-border: @state-info-border;
@panel-info-heading-bg: @state-info-bg;
@panel-warning-text: @state-warning-text;
@panel-warning-border: @state-warning-border;
@panel-warning-heading-bg: @state-warning-bg;
@panel-danger-text: @state-danger-text;
@panel-danger-border: @state-danger-border;
@panel-danger-heading-bg: @state-danger-bg;
//== Thumbnails
//
//##
//** Padding around the thumbnail image
@thumbnail-padding: 4px;
//** Thumbnail background color
@thumbnail-bg: @body-bg;
//** Thumbnail border color
@thumbnail-border: #ddd;
//** Thumbnail border radius
@thumbnail-border-radius: @border-radius-base;
//** Custom text color for thumbnail captions
@thumbnail-caption-color: @text-color;
//** Padding around the thumbnail caption
@thumbnail-caption-padding: 9px;
//== Wells
//
//##
@well-bg: #f5f5f5;
@well-border: darken(@well-bg, 7%);
//== Badges
//
//##
@badge-color: #fff;
//** Linked badge text color on hover
@badge-link-hover-color: #fff;
@badge-bg: @gray-light;
//** Badge text color in active nav link
@badge-active-color: @link-color;
//** Badge background color in active nav link
@badge-active-bg: #fff;
@badge-font-weight: bold;
@badge-line-height: 1;
@badge-border-radius: 10px;
//== Breadcrumbs
//
//##
@breadcrumb-padding-vertical: 8px;
@breadcrumb-padding-horizontal: 15px;
//** Breadcrumb background color
@breadcrumb-bg: #f5f5f5;
//** Breadcrumb text color
@breadcrumb-color: #ccc;
//** Text color of current page in the breadcrumb
@breadcrumb-active-color: @gray-light;
//** Textual separator for between breadcrumb elements
@breadcrumb-separator: "/";
//== Carousel
//
//##
@carousel-text-shadow: 0 1px 2px rgba(0,0,0,.6);
@carousel-control-color: #fff;
@carousel-control-width: 15%;
@carousel-control-opacity: .5;
@carousel-control-font-size: 20px;
@carousel-indicator-active-bg: #fff;
@carousel-indicator-border-color: #fff;
@carousel-caption-color: #fff;
//== Close
//
//##
@close-font-weight: bold;
@close-color: #000;
@close-text-shadow: 0 1px 0 #fff;
//== Code
//
//##
@code-color: #c7254e;
@code-bg: #f9f2f4;
@kbd-color: #fff;
@kbd-bg: #333;
@pre-bg: #f5f5f5;
@pre-color: @gray-dark;
@pre-border-color: #ccc;
@pre-scrollable-max-height: 340px;
//== Type
//
//##
//** Text muted color
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How Quantum Entanglement Reshapes Information Understanding | JNP Sri Lanka | National Freedom Front
1. Introduction: Redefining Information in the Quantum Age
Traditional information theories, rooted in classical physics and Shannon’s foundational work, conceptualize data as independent, localized bits that can be measured and transmitted without fundamental constraints on their correlations. These models have served well in everyday communication and computing but encounter limitations when faced with phenomena at the quantum scale, where entanglement challenges classical notions of locality and causality.
The advent of quantum mechanics introduced a radically different perspective: particles can become intertwined such that the state of one instantly influences the state of another, regardless of distance. This phenomenon, known as quantum entanglement, compels us to rethink how information is structured, transferred, and stored at fundamental levels.
This article explores how quantum entanglement is not merely a peculiar quantum effect but a transformative principle that reshapes our entire understanding of information, bridging abstract scientific concepts with real-world applications like quantum computing and secure communication. deep navy backdrop chills serve as a metaphor for the mysterious depths of quantum phenomena, illustrating the profound shift in our conceptual framework.
a. What is quantum entanglement? Definitions and core principles
Quantum entanglement describes a phenomenon where two or more particles become linked such that the state of one instantaneously influences the state of the other, regardless of the distance separating them. Unlike classical correlations, which arise from shared history or common causes, entanglement involves a holistic quantum state that cannot be factored into independent parts.
For example, if two photons are entangled in polarization, measuring the polarization of one immediately determines the polarization state of the other, even if they are light-years apart. This “spooky action at a distance,” as Einstein called it, defies classical intuitions and exemplifies the fundamentally non-local nature of quantum mechanics.
b. Historical development and key experiments (e.g., Bell tests)
The concept of entanglement was first introduced by Erwin Schrödinger in 1935, emphasizing its foundational importance. The pivotal moment came with John Bell’s work in the 1960s, where he formulated inequalities that could distinguish between classical local realism and quantum predictions. Subsequent experiments, notably those by Alain Aspect in the 1980s, confirmed violations of Bell inequalities, providing strong evidence for entanglement’s reality and its non-classical nature.
c. Comparing classical correlations with entanglement-induced correlations
Classical Correlations
Quantum Entanglement
Arise from shared history or local causes
Involve non-local, holistic quantum states
Can be explained by classical probability
Violates classical inequalities (Bell tests)
Limited by classical physics
Fundamental to quantum mechanics
3. The Paradigm Shift: From Classical to Quantum Information
a. How classical information theory views data and communication
Classical information theory, pioneered by Claude Shannon, considers information as discrete bits—0s and 1s—that can be reliably transmitted over channels with certain capacities. It assumes locality, where information is stored and transmitted through well-defined physical carriers, and that the correlations between data points are explained by shared causes or prior states.
b. Limitations of classical models in explaining quantum phenomena
Classical models cannot account for entanglement’s non-local correlations. For instance, classical physics cannot explain how measurements on entangled particles instantaneously influence each other without violating causality or requiring superluminal signals. This limitation led to the development of quantum information theory, which incorporates principles like superposition and entanglement as fundamental resources.
c. Introduction to quantum information theory and its foundational differences
Quantum information theory extends classical concepts by considering qubits—quantum bits—that can exist in superpositions of 0 and 1. Unlike classical bits, qubits can be entangled, enabling phenomena like quantum teleportation and superdense coding. These capabilities fundamentally change how information can be processed, transferred, and secured, opening new technological frontiers.
4. Quantum Entanglement as a Resource for Information Processing
a. Entanglement in quantum computing: superposition vs. entanglement
Quantum computing leverages both superposition and entanglement. While superposition allows a qubit to be in multiple states simultaneously, entanglement links qubits so that the state of one directly influences others. This interconnectedness enables quantum algorithms, such as Shor’s algorithm for factoring large numbers, to outperform classical counterparts significantly.
b. Implications for secure communication: quantum cryptography
Quantum cryptography, especially Quantum Key Distribution (QKD), uses entanglement to generate intrinsically secure communication channels. Any eavesdropping attempt disturbs the quantum states, revealing the intrusion and ensuring privacy. Protocols like BB84 and E91 demonstrate how entanglement underpins unbreakable encryption schemes.
c. Error correction in quantum systems and the importance of low error rates (<10^-4)
Quantum error correction is vital due to the fragile nature of qubits and the high error rates caused by decoherence. Achieving error rates below 10-4 is essential for practical quantum computing. Techniques like surface codes and entanglement-assisted error correction utilize entanglement to detect and fix errors without destroying quantum information.
5. Reshaping Our Understanding of Information Transfer and Storage
a. Non-locality and instant correlations: challenging classical causality
Entanglement introduces non-locality, where entangled particles exhibit correlated outcomes instantaneously, defying classical causality constraints. This phenomenon suggests that information transfer does not always conform to the traditional cause-effect paradigm, prompting revisions in our understanding of space, time, and causality.
b. Entanglement swapping and quantum teleportation as new information paradigms
Entanglement swapping allows entanglement to be transferred between particles that have never interacted directly, while quantum teleportation transmits a quantum state from one location to another without moving the physical particle. These processes redefine what it means to transfer and store information, moving beyond classical notions of data movement.
c. The role of entanglement in distributed quantum networks
Distributed quantum networks rely on entanglement to connect qubits across vast distances, enabling secure communication and distributed quantum computing. These networks function as a new form of information infrastructure, where entanglement provides a non-local resource that underpins the entire system.
6. Analogies and Examples: Bridging Abstract Concepts and Practical Scenarios
a. The «Chicken vs Zombies» analogy as a modern illustration of entanglement-like coordination
Imagine a scenario where chickens and zombies are part of a game: if a chicken hides in one location, a zombie in another reacts instantly, regardless of the distance. This mirrors entanglement’s non-local correlations—actions on one part immediately influence the other, even without a direct connection. The deep navy backdrop chills of this analogy evoke the mysterious depths where quantum entanglement operates, illustrating how coordinated responses can defy classical explanations.
b. Classical vs. quantum game strategies: how entanglement changes outcomes
In classical game theory, players’ strategies are independent, limited by local information. Quantum strategies, utilizing entanglement, enable correlated moves that can outperform classical equilibria. For example, in the “CHSH game,” entangled particles allow players to win more often than any classical strategy permits, exemplifying how entanglement enhances collaborative decision-making.
c. Real-world applications: quantum internet, secure communication, and computation
Practical applications are emerging as quantum technologies mature. Quantum internet, leveraging entanglement, aims to connect quantum processors over large scales, enabling ultra-secure communications and distributed quantum computing. These innovations promise to revolutionize fields from cybersecurity to complex simulations, grounded in the fundamental principles of entanglement.
7. Deep Dive: Mathematical and Theoretical Foundations
a. The role of the Navier-Stokes equations and unsolved problems in modeling complex systems
The Navier-Stokes equations govern fluid dynamics but remain partially unsolved, illustrating the difficulty of modeling complex, chaotic systems. Similarly, understanding entanglement involves grappling with complex mathematical structures that challenge current computational and analytical tools, pushing the boundaries of physics and mathematics.
b. How mathematical challenges relate to understanding quantum information
Quantum information theory relies heavily on linear algebra, tensor networks, and quantum entropy measures. Solving problems like efficiently simulating entangled states and understanding quantum error correction codes requires advances in mathematics, akin to tackling the Navier-Stokes Millennium Prize Problem—an unresolved challenge that could unlock deeper insights into the fabric of quantum data.
c. The significance of prime number theories (e.g., Riemann hypothesis) as metaphors for hidden structures in quantum data
Prime number distributions, such as those conjectured in the Riemann hypothesis, symbolize the hidden structures underlying complex systems. Similarly, quantum data may harbor concealed patterns—exploited by advanced algorithms—to optimize information processing and cryptography, revealing that the universe’s deepest secrets may be woven into the mathematical fabric of quantum states.
8. Implications for Future Technologies and Scientific Inquiry
a. Potential breakthroughs enabled by quantum entanglement
Harnessing entanglement could lead to revolutionary breakthroughs such as unbreakable encryption, faster-than-classical computation, and ultra-precise sensors. Quantum networks might enable seamless, secure global communication, fundamentally transforming data security and processing speeds.
b. Challenges in harnessing entanglement: error rates, decoherence, scalability
Despite promising prospects, practical implementation faces hurdles like maintaining entanglement over long distances, reducing error rates below 10-4, and scaling up quantum systems. Decoherence—the loss of quantum coherence—remains a significant obstacle requiring innovative solutions in materials and system design.
c. The philosophical shift: from deterministic classical models to probabilistic quantum realities
Quantum entanglement underscores a fundamental shift from deterministic classical physics to a probabilistic universe, where information and outcomes are inherently uncertain until measured. This philosophical transition influences not only science but also our worldview about reality and knowledge itself.